15 replies to this topic

[OdanUrr87]

Updated as of August 1, 2011.


The following is a guide to re-coloring and retexturing an already existing item in Dragon Age 2, more specifically, armor. This guide is based in no small part in my own experience so it's probably far from complete but I believe it does cover the basics. I myself have used Photoshop CS4 to retex armors, therefore this guide reflects that. Furthermore, I will assume the reader of this guide is familiar with, at least, the following concepts:

• Using the "Rectangular Marquee Tool," the "Lasso Tool," or the "Quick Selection Tool," to select a specific part of an armor.
• Using layers (creating, rearranging, and editing them).

Last but not least, I will also assume that the reader has access to the diffuse, specular, and normal maps, belonging to a specific set of armor.

Let us begin then.


Diffuse, Specular, and Normal Maps


If you want to know in detail the differences between the three of them, it is recommended you pay a visit here:
http://social.bioware.com/wiki/datoolset/index.php/Textureformats

If you've skipped the link, however, you probably want the short version:

• The diffuse map is the one you need to edit when all you want to do is change color (e.g.: you want a red cape and you have a blue one, this is where you need to go.)
• The specular map also has a color map, but this color map deals with the armor's reflections, that is, the manner in which it will reflect light (e.g.: now that you have the red cape, you notice that when light reflects on it, it has a sort of purplish glow. Say you want it to have a greenish sort of glow, then edit this map).
• The normal map is a *censored* and it has to do with textures. You'll notice different heights and depths here, these correspond to how you will see the armor in the game. This map gives the notion of 3D.

Now, don't go panicking on me yet. Trust me, there's plenty of time for that later. If all you want to do is change the color of an item, you'll never have to deal with the specular and normal maps (unless you also want to change the glow, in which case you'll need to edit the specular map as well). If, on the other hand, you also want to change a leather helmet into a metallic one, you'll probably have to deal with all three of them.

Tip: When editing any piece of armor, I suggest you create a folder for each map you edit. Backing up your progress from time to time will also help you avoid pretty destructive mistakes.


Alpha Channel


The Alpha Channel is pretty useful when working with diffuse maps, and extremely annoying in the case of the other two. In a diffuse map, you can use it to hide things you don't want to see in the game. In the specular and normal maps, this channel has information on textures, meaning that, not only you will have to edit the RGB channel of each one, you will also have to edit the Alpha Channel on both.

If you're reading this, then none of this should make sense to you, or you wouldn't be reading it in the first place. You'll only truly learn by trial and error, but the next best thing is an example with a few carefully placed images. We'll be using beeto's "Heavy Female Warden Armor" (many thanks to him) since that's the one that got me into this whole mess in the first place.

You'll find beeto's "Heavy Female Warden Armor" here:
http://www.dragonagenexus.com/downloads/file.php?id=2793

You will also need the following NVIDIA plugin to load and save .dds files with Photoshop:
http://developer.nvidia.com/nvidia-texture-tools-adobe-photoshop


Next post --> Editing the Diffuse Map

(please refrain from replying to this thread until this message is no longer present)

Edited by OdanUrr87, 01 August 2011 - 01:47 PM.

[OdanUrr87]

Example - Part 1: Editing the Diffuse Map


beeto has kindly already uploaded the .dds files for his armor, so you can simply download them from the link. Before doing anything, let's take a look at hf_arm_wmda_0d.dds using Photoshop (when loading the .dds files, leave the NVIDIA settings as they are):



Yes, what you're seeing are parts of Bethany's Grey Warden Armor, but you already knew that. You may have realized one glaring difficulty already: what exactly is it that I'm editing in the game? Well, my answer to that is "Get used to opening and closing Dragon Age 2 a hundred times in the foreseeable future" (if you've got eidetic memory, make that one time).
To simplify matters (I'm lazy too) we'll be editing the two large rectangles in the picture at the top right and bottom left corners. These two rectangles constitute the skirt we see at Bethany's back in the game. We'll be changing the image into the following:



As you can see, that means we'll be re-coloring AND retexturing. Get ready for a long ride.

Organize the hf_arm_wmda_0d.dds, hf_arm_wmda_0s.dds, and hf_arm_wmda_0n.dds, into their corresponding folders (diffuse, specular, normal), open (if you haven't done so already) the diffuse map with Photoshop, and save it as a PSD file. You have the same background image as before, and it is still locked out. Unlock it by double-clicking on it in the Layers window and create "Layer 0" when prompted to do so.

Let's start by changing the top right corner rectangle from blue to black.

This is what I do. First I duplicate the image (Image --> Duplicate), then convert that duplicate image into Grayscale mode (Image --> Mode --> Grayscale), and then back into RGB color mode (Image --> Mode --> RGB color). Why? Simply put, because someone told me to do so. The longer explanation is that now you have a "blank" RGB copy of your diffuse map that will come in handy when actually editing that map. Now right-click on it, select "Duplicate Layer," choose your PSD file as the destination document and hit OK. You should now have two layers in your PSD file, "Layer 0" (your original image) and "Layer 1" (your "blank" RGB copy). Now that's over and done with you can get rid of the duplicate and stick to your PSD.
From "Layer 1" you will create any number of layers to replace parts of the armor. For instance, let's start by selecting the top right corner with one of the selection tools (I'd suggest going for the Rectangle Marquee here):



Right-click on your selection and choose "Layer via Copy." Why layer via copy and not layer via cut? One word: backup. If you messed up with the selection or whatever, choosing layer via copy will leave your Layer 1 pristine, untouched, in the perfect conditions for you to make many more mistakes. If you choose layer via cut, there's no turning back (the rhyme was a lucky accident).

WARNING: MAKE ABSOLUTELY SURE that Layer 1 is currently selected (meaning it's highlighted in blue) when you select layer via copy. If, say, Layer 0 is selected instead, you will end up with a blue rectangle because it's copying from Layer 0 instead of from Layer 1. If you have selected a blank layer it will create a blank layer in turn. Watch out. Yet another reason to choose layer via copy.

Let's hide Layer 1 for the time being. You should now be seeing a grey rectangle overlapping your original blue rectangle. That's not good enough, I want it darker. Right-click on "Layer 2" and select "Blending Options."



Now, this is my MAIN tool for re-coloring pretty much anything. If you know another, good for you. My knowledge on this tool extends so far as messing with the RGB channels (go ahead and mess with them yourself and see how your rectangle changes color) and using some of the effects on the left column.

But before we move any further let's dwell a bit on the RGB channels. If you've done as I asked and messed with them a bit, you should have noticed there are some colors you can't see. Try selecting the G channel only. Can you see green anywhere? No. Why? Well, if I had to venture a guess, I'd say there's a conflict between the RGB channels of Layer 2 and Layer 0. Turn off Layer 0. Presto, green everywhere! Is there a way around this? Yes, I know of one, and it isn't pretty. It's a curse word known in Photoshop as "Convert to Smart Object," and let me give you a free piece of advice on this one:

NEVER SAVE YOUR PSD FILE IF IT HAS SMART OBJECTS IN IT!!!

Because if you do so, you'll be effectively turning it into an image, and even if you rasterize the layer, you won't be able to edit your original "Blending Options" and will instead be handed a set of new ones. What do I mean by this? First, save your PSD file. Then right-click on Layer 2 (make sure you can now see Layer 0) and select "Convert to Smart Object." Now check the blending options of Layer 2. Surprise, surprise, all three channels (R, G, and B) are now enabled again, when you should only have the G channel enabled! Undo this mess by hitting Ctrl+Z on your keyboard (or Alt+Ctrl+Z if you've made many messes).

Back to blending options, leave all three channels enabled and instead go to "Color Overlay." The name should be self-explanatory but if you still don't get it, I'm sure the big, bright, red brick on your screen will suffice to enlighten you. You have three options here:

• Blend Mode: Play with it and learn on your own (for now, leave it on Normal).
• Select Color: We'll we choosing (0,0,0) here.
• Opacity: Dial it down to 70%.

Success! This part of the skirt is now a blend between dark grey and black. It may be crude and brutal but it's effective.



Now for the other part. Select Layer 1, make an appropriate selection and create another layer via copy. Your selection should look something like this:



Following the same procedure as before, re-color it into the dark grey/black blend. Before moving on, remember what I said about rearranging layers? Move Layer 3 to the bottom and watch the results. Yup, the order of layers in the Layers window matters, remember that. Next, we're going to make two more selections and two more layers, one for each textured stripe. This is what I mean:



Layers 4 and 5 are a stripe each. Move them above Layer 3 or you'll never notice the difference. Now we need to find the texture.

Spiderman pattern by s0nkite:
http://www.brusheezy.com/Patterns/1311-Spiderman-Pattern--a-cool-mesh-pattern-

Install it following the instructions in the link, but seeing as that only works halfway, once you've pasted the pattern in the appropriate folder, double-click on it and you're good to go. Select each of the stripes, go to blending options, and choose "Pattern Overlay." Choose s0nkite's pattern here and don't even bother changing opacity. You can mess with the scale a bit to get the pattern the way you want it to. Right now, you want it with a scale factor of 50%. Here I'm using a specific pattern but you can use any that you like for your future endeavors. Next go to color overlay, and choose a black overlay of 80% opacity. Nice, isn't it? Do the same with the other stripe.

This is it for the diffuse map. However, what you have at the moment is a PSD file when what you really need is a DDS file. Follow these steps VERY carefully:

• Save your PSD.
• Right-click on any layer and select "Flatten Image." It'll ask you if you want to discard any and all hidden layers. As long as the map is looking the way you want it to, hit OK. The result is a single locked out image not unlike the one you had when you started.
• Go to File --> Save As (DO NOT SAVE! SAVE AS!)
• Save As DDS (DO NOT OVERWRITE THE PSD! Somewhere along the lines of these tutorial it changed my file name and added "copy" at the end. This was because I already had a PSD file with that name on the same folder so don't worry, it shouldn't happen to you. Your filename should read "hf_arm_wmda_0d.dds")
• You'll be prompted with the NVIDIA saving window. Don't panic, choose the DXT5 ARGB format and hit the save button.
• Now your Photoshop shows you have the DDS file open. Don't worry, the PSD is still there in the folder, safe and sound.

Congratulations! Your work here is finished, but before we move on, let's discuss the use of the alpha channel in the diffuse map. Go to the Channels windows and select the Alpha Channel. If RGB is enabled as well, you should see that certain parts of the map are red. If you turn off RGB, you'll see that the red part is really black, and everything else is white. Meaning what? Meaning that, if the red/black parts are pieces of an armor, those pieces won't show up in the game. You can see for yourself. You only need to select the Alpha Channel (RGB still enabled) and, using the selection tool, create any shape over a piece of armor and fill it with black (right-click on selection, fill, black). If you've changed your mind and actually want to see the thing, simply turn the black part into white via another selection and fill.

NEW: You learn something new everyday. Hiding parts of an armor via the alpha channel is only the first step. For the second step you need to edit the respective .mao file, in particular, you need to change line 33013 from the .mao file from whatever it might say to "PunchthroughNoTint." Someday I'll expand on the use of .mao files but this should be enough to get you going.

Moving on.


Next post --> Editing the Specular Map

(please refrain from replying to this thread until this message is no longer present)

Edited by OdanUrr87, 01 August 2011 - 01:46 PM.

[OdanUrr87]

Example - Part 2: Editing the Specular Map


Ah, this is where the fun begins. And by fun, I mean you have to work twice as much. And by you, I actually mean YOU since I have already done this so I'll simply cheat on you by using a specular map that already has the layers I want. Not to worry, the following steps should minimize the time you spend here.

Go to the specular folder and open the Specular Map. A little tip that'll explain why I'm about to do what I'm about to do: the specular and normal maps are 50% smaller than the diffuse map. That means that anything you scaled in your diffuse map, you'll have to scale to half that number in the specular and normal maps. This also means that you can't cheat your way by duplicating layers from the D map into an S or N map (I mean, you probably could, you'd need to scale it, but that's not how I roll, meaning I haven't tried it).

You know the drill, save it as a PSD and create Layers 0 and 1 same as you did with the diffuse map. Now, remember what the S map was, right? Light, reflection, Newton. Well, not that last part, but the other two definitely. Turn off Layer 1 and take a look at Layer 0 for five seconds. The dark parts in your D map are pretty dark here too. You can, if you wish, create layers from Layer 1 and mess with brightness, or contrast, or color, or whatever, to change the way those dark parts will reflect the light. Fortunately, you're not in the mood for it and will only change the texture of the stripes.



Boy, I'm fast, took me a full ten seconds (cheating, remember?). Each stripe has the same color overlay (black, 80% opacity) and the same pattern (s0nkite's Spiderman pattern), BUT the scale factor for the pattern is 25% to maintain proportions (remember the S map is 50% smaller than the D map). The stripes needn't have the same color overlay, mind you, I just did that out of practicality. You could have chosen a white overlay with 20% opacity for all I care. What you must remember is to maintain pattern proportions from D to S map. This also applies to the N map.

Finished, yes?

Not by a long shot.

Go to the channels windows, turn off the RGB channel and turn on the Alpha Channel. Oh, yes, you have the original pattern here as well. There's no way around it (that I know of), you have to edit the Alpha Channel too.

Here's what you do, select the Alpha Channel, then Ctrl+A (Select All) and Ctrl+C (Copy). With the selection visible, go to New and hit OK (you needn't worry about dimensions since Photoshop assumes you will try and paste what you've just copied into a new file and assigns the dimensions accordingly). Save this new file as a PSD (you may call it "alpha" or "hf_arm_wmda_0d alpha," but DO NOT overwrite your first PSD, this one is a very different and equally important PSD).

By now, you might have guessed where this is going. You can see that the image you have here is an exact copy of your original alpha channel. We're going to tweak this copy and paste it into the alpha channel of our first PSD. Go back to your original PSD and deselect your selection if you haven't done so already. Good news is you can simply duplicate the layers corresponding to the stripes into the alpha PSD. This is what I do to save time. Alternatively, the same process that applies to the D or S maps applies to the alpha PSD (duplicate image, you'll notice it's already in Grayscale mode, DO NOT convert into RGB color mode, simply duplicate this copy image into your alpha PSD, create selections, create layers, etc.).

When all is said and done, your alpha PSD should look like this:



NOTE: What are the benefits of having the alpha PSD? Really? Two words: future projects. Anytime you want to edit a texture, you have to edit the alpha channel of the S map.

What you want to do now is the following:

• Save your alpha PSD.
• Right-click on any layer in the alpha PSD and select "Flatten Image."
• Ctrl+A and Ctrl+C.
• Go to your original PSD and select the alpha channel (make sure that the alpha channel is on and selected and that the RGB channel is off).
• Ctrl+V and deselect selection.
• Close your alpha PSD without saving (you already saved it before, remember?).

Damn, you're good. You've just edited the RGB and Alpha channels of the S map. Now you need to save it as a DDS:

• Save your PSD.
• Right-click on any layer and select "Flatten Image." It'll ask you if you want to discard any and all hidden layers. As long as the map is looking the way you want it to, hit OK. The result is a single locked out image not unlike the one you had when you started.
• Go to File --> Save As (DO NOT SAVE! SAVE AS!)
• Save As DDS (DO NOT OVERWRITE THE PSD! Your filename should read "hf_arm_wmda_0s.dds")
• You'll be prompted with the NVIDIA saving window. Don't panic, choose the DXT5 ARGB format and hit the save button.
• Now your Photoshop shows you have the DDS file open. Don't worry, the PSD is still there in the folder, safe and sound.

Basically, the same procedure as the D map.


Next post --> Editing the Normal Map

(please refrain from replying to this thread until this message is no longer present)

[OdanUrr87]

Example - Part 3: Editing the Normal Map


Time for the coup de grace. That's one scary, orange mothe... I mean, bloke. The process here is pretty much a carbon copy of Part 2, but I'll take you through it anyway.

Create Layer 0 by double-clicking where it says "Background" in the layers channel, then save your file as a PSD. Instead of going through the whole "duplicate image" phase, right-click on Layer 0 and select "Duplicate Layer." You may name it as you wish, though I'll name it Layer 1 for simplicity. The N map is strictly reserved (for me, at least) for textures, so the only thing I'm going to edit here are the stripes I've already edited in the previous D and S maps.

Like before, use Layer 1 to create new layers for each stripe. Also like before, use the s0nkite pattern with a scale factor of 25%. UNLIKE before, your color overlay needs to be orange because the pattern needs to be the same color as the rest of the map. You can use the Eyedropper Tool if you like, to obtain RGB parameters for the orange color of the N map (it has several, naturally, but one will do). In this example, I'm using (255, 100, 0) at 80% opacity.



It shouldn't come as a surprise that the alpha channel here, same as with the S map, likes messing with you and therefore retains the original texture instead of s0nkite's. Not to worry, you've dealt with the alpha channel of the S map and this is no different:

• Select the alpha channel (that is, ON + Selected) and make sure the RGB channel is offline.
• Ctrl+A and Ctrl+C.
• File --> New and hit OK.
• Ctrl+V on the new file and save as a PSD (do not overwrite the original PSD, create a new one, maybe using "alpha" as reference).
• Go back to your original PSD and deselect selection if you haven't done so already. Turn off the alpha channel, select and turn on the RGB channel (maybe this part is unnecessary, but it doesn't hurt). Duplicate the layers corresponding to your stripes (in my case these are Layers 2 and 3) into the alpha PSD.
• You'll notice that, much like the S map, the stripes are gray (because you only have the Gray channel in this alpha PSD). Save the alpha PSD, flatten image, Ctrl+A and Ctrl+C, return to your original layer and select (ON + Select) the alpha channel only, then Ctrl+V.
• Close the alpha PSD without saving.
• Turn off the alpha channel, enable the RGB channel.
• Save your PSD.
• Right-click on any layer and select "Flatten Image." It'll ask you if you want to discard any and all hidden layers. As long as the map is looking the way you want it to, hit OK. The result is a single locked out image not unlike the one you had when you started.
• Go to File --> Save As (DO NOT SAVE! SAVE AS!)
• Save As DDS (DO NOT OVERWRITE THE PSD! Your filename should read "hf_arm_wmda_0n.dds")
• You'll be prompted with the NVIDIA saving window. Don't panic, choose the DXT5 ARGB format and hit the save button.
• Now your Photoshop shows you have the DDS file open. Don't worry, the PSD is still there in the folder, safe and sound.

Next post --> Checking your work ingame

(please refrain from replying to this thread until this message is no longer present)

[OdanUrr87]

Showing off


This is nice and all, but what of the armor? Has it changed in the game? Well, no, you need to create a proper ERF package. What do I mean by "proper"? Just that it needs to be structured, folder-wise, in such a way that the game will look for the textures in the correct folders.

For this you'll need two things:

• The GFF editor: http://social.bioware.com/project/1936/
• The ERF packer: http://social.bioware.com/project/4419/

Take beeto's "Heavy Female Warden Armor." Locate the ERF file corresponding to the textures ("hvy_fem_wrd_txtrs.erf") and export it all using the GFF editor. If done right, you'll have a new folder called "art" and the corresponding set of subfolders:

...\characters\playercharacter\humanfemale\textures

Not surprisingly, this looks awfully similar to what you get if you extract DA2's "artfp.erf" (plus/minus a few odds and ends). Why is that? Because the armors/clothing in the game can be found and are looked for in this directory. What's going on here is that you're adding a new set of armor to this directory by the name of (arm/boo/glv)_wmda.(mao/mmh/msh/phy) and its corresponding textures (D, S, and N maps for each piece).

I've assumed thus far that you are already familiar with manipulating the item_variations.gda file to associate a particular set of armor with the armor you want, for this is exactly what needs to be done for you to have this armor in the game (if you don't, here's an excellent guide: http://social.bioware.com/forum/1/topic/307/index/6557648). So assuming you had this armor all along, the only thing you need to do now is repackage the "hvy_fem_wrd_txtrs.erf" with your modified D, S, and N maps.

First replace the original maps with your own. Then create a new folder named as the original ERF (that is, "hvy_fem_wrd_txtrs") and copy the "art" folder into it. Move the folder "hvy_fem_wrd_txtrs" over "Gibbed.Bioware.ErfPack.exe" (the executable for the ERF packer) and the ERF will be automatically created in the same directory where your "hvy_fem_wrd_txtrs" folder is at. Replace the old "hvy_fem_wrd_txtrs.erf" file with your new one and you're good to go.

Here's the before of the armor's skirt:



And here's the after:



Not perfect but it does get the job done. As you can see it doesn't glow very much, but that's because of the opacity of the color overlay used in the specular map. You can play with that and any of the dozens, if not hundreds, of tools Photoshop has at your disposal to tweak images. Also, it may appear some of the stripes are thinner than in the original model. Well, that'll depend on your ability to select and create layers on all maps.

Ultimately, this is a very basic guide because my own knowledge of the subject is limited and goes no further than a few days ago. It's intended to jump start you so that you don't have to figure this much on your own. From this point onwards you may learn a lot more tricks that can perhaps be added to this guide. In fact, any input from experienced modders is more than welcome. If we can turn this into a dynamic guide, then so much the better.

So go now, reskin something, and then come back and share your results with us, be it in the form of images or mods. Remember that reskinning takes time and requires patience, so that every mod out there is a tribute to their creator, to the effort they've put into creating something for us, something that we can enjoy.

So, to all the modders out there, thank you!

To all you future modders, welcome!


**NEW**Cutting down retex time by 2/3**NEW**


Remember when I said you couldn't just duplicate a layer from the D map onto the S and N maps? Well, that's not quite true. It's doable, and it should cut down retex time by 2/3 (it's a generous estimate since this process takes some time too, but at least you won't have to make the same selection thrice).

What you want to do is this:

• Assuming you've finished with the D map in Photoshop, leave your D map PSD open and open, for instance, the S map .dds file.
• Select this image (Ctrl+A), copy it (Ctrl+C), and go to "New-->File" and hit Enter. This should create a blank image (probably under the name, "Untitled-1") that matches the size of the S map. You can now close the S map .dds file and open the S map PSD file.
• Go to your D map PSD, select any given layer, and duplicate this layer into "Untitled-1." Go back to "Untitled-1." Odds are you're seeing nothing here. Select the Move Tool (V) and use it on the blank image until your layer pops up. You'll see it's a bit large compared to its surroundings, but that's because it has yet to be scaled down to match the size of the S map. Go to "Edit-->Transform-->Scale" and scale it down to 50%.
• Now all you have to do is duplicate this new layer into your S map PSD and that's it. You can also duplicate it into your N map PSD if you're messing with textures (same goes for the alpha channel PSDs of the respective maps). However, if the layer you're working with has a different texture than the original, remember you have to adjust the pattern to 50% of the value from the D map, both on the S and N maps.

Acknowledgments


My thanks to beeto for letting me use the "Heavy Female Warden Armor" mod as an example, and also to Aremeta for putting up with my relentless stream of questions about reskinning. I'd also like to thank any and all modders who will add to this guide in the near, and not so near, future.

Edited by OdanUrr87, 24 June 2011 - 07:39 PM.

[gambit51]

thanks for taking the time to make this guide
kudos to you

[Ulaume]

Thank you very much for this, very helpful to nooby me Hopefully will be able to create something nice when have the time.

~ Lormy

[Ulaume]

I'd like to know how to make parts of an armour invisible, as has been done with that heavy female warden armour with the part that was originally Meredith's.  If I wanted to, say, remove the breastplate from that, what would I need to do?  I know it has something to do with the alpha channels plus the .mao file, I'm not sure what one would need to do or which settings one would need to use etc.

Another thing I'd like to know, which I imagine is actually rather straight forward Photoshop but I'm not familiar with it, is how to use a texture from one thing on another thing.
 Example, I see many people making the female warden trousers chainmail, looks like the same texture from Bethany's pre-warden armour, which I'd like to use on some things too.
I'd like to know how I would go about copying a texture I liked from a dds file and using it in another.

Hope someone might help

~ Lormy

[eleglas]

Thanks for this guide. While I already know how to edit textures (been doing it since Oblivion). But I will be adding this guide to my links in my pinned topic "What DA2 mods are possible - and why so few", it will help people find it.

Kudos to you for this, and thanks for the guide.

[OdanUrr87]

I'd like to know how to make parts of an armour invisible, as has been done with that heavy female warden armour with the part that was originally Meredith's.  If I wanted to, say, remove the breastplate from that, what would I need to do?  I know it has something to do with the alpha channels plus the .mao file, I'm not sure what one would need to do or which settings one would need to use etc.

Another thing I'd like to know, which I imagine is actually rather straight forward Photoshop but I'm not familiar with it, is how to use a texture from one thing on another thing.
 Example, I see many people making the female warden trousers chainmail, looks like the same texture from Bethany's pre-warden armour, which I'd like to use on some things too.
I'd like to know how I would go about copying a texture I liked from a dds file and using it in another.

Hope someone might help

~ Lormy

1) To make parts of an armour invisible you need to mess with the alpha channel of the D map. If you have no alpha channel you need to create one (very simple, go to the Channels windows and click on the icon that says "Create new channel"; in my Photoshop it looks like you're turning a page). I mentioned this on the guide already but there's no harm in repeating it. Let's break it down to the following two cases:

a) You already have an alpha channel on the D map --> If you select the RGB + Alpha channels you'll notice there are spots of red all over. Turning off the RGB channels you'll notice the red is actually black, and the rest is white. This means that when you want to hide something from view in the game, you need to make a selection of the part of the armour you want to hide, right-click that selection and fill it with black (all of this must be done in the alpha channel). If you want to try it, turn on the RGB + Alpha channels but make sure you're working on the Alpha (meaning it's highlighted in blue). You'll see the armour and spots of red. Make a selection of, say, the collar of an armour, right-click it and fill it with black. Now the collar of the armour shouldn't appear in the game.

b) You don't have an alpha channel on the D map --> Create one like I said in 1). In all likelihood, the created alpha channel will be entirely black. Fill it with white and then repeat the process in a).

I don't know about editing the .mao files to hide a portion of the armour. For me it has always worked using a) or b).

2) This one's a bit trickier but not impossibly so. Let's take Bethany's Warden Armour as an example. Suppose you want to use her trousers' texture to cover a part of, let's say, her arm. You know, the patch of her arm that seems to be covered in a reticular pattern of tiny squares. You have your Layer 1 (as explained in the guide), make the selection of the portion of her arm you want to cover. Move this selection over to the trousers, the texture you want to use to cover her arm. If you're not comfortable with the patch of trousers your selection shows, you can rotate your selection to choose a different patch. You can do this by going to "Select --> Transform Selection," here you can modify dimensions or rotate at will. Once you have the patch of trousers you want, create a layer via copy. Select this new layer and move it to the portion of her arm you want to cover. Obviously, since you've rotated it, it won't cover it properly. Here you go to "Edit --> Transform --> Rotate" and you rotate it again to match the portion of her arm you want to cover. Presto! You've just learnt to use one part of her armour to cover another.

If I ever get around to posting this as a wiki article I'll add this and maybe include some pictures.

Hope it helps!