I've never used this feature, haven't done any kind of edits to characters. But I was curious so I gave it a shot. Managed to put a beard on Wiseman
. Some beards have extra parts - hairline. I used BigBeard07 and its hairline. I duplicated both beard and hairline and created new forms. I set the valid races to be HeadPartsGhouls. Then I opened the new beard and deleted the existing extra head part and added the duplicated hairline there. Went to Wiseman's actor form, Character Gen Parts -> Base Head Parts, selected Facial Hair. From the dropdown menu below the Base Head Parts I chose the newly created beard. Then Clicked at Preview -> Head. And Wiseman's face appeared with a beard. Some of the things that the preview does not show are the color of the hair and the eye color. Every time you change a head part, you have to click on Preview->Head in order to update the preview window. Not seeing the color doesn't mean that it's not going to change, but you'll have to test it in the game to see how it looks. Keep in mind that the mesh of the head and head rear for male ghouls is different than human one. That's why hair styles and beards may not look good(not fit well on the head) with some clipping issues. Not sure why they did that, since the ghoul and human female head meshes are almost identical, minus the missing nose.
If you want to add Scars/Face Details/Skin Tints to ghouls. Right click on Scars(on the black bar) -> Add -> choose a scar from the new window. Select the newly added scar and go to Face Tinting Color(it is above the Base Head Parts) and increase the Value to make the texture more opaque(meaning 1.00 to make it fully appear). Same goes for the Face Details. These are all updated on the preview window. For the Skin Tint, you just select the Skin tone and instead of Value, you use the dropdown menu called Preset. Skin tone is updated on the preview window too.
Thank you both very much for the responses! 
I managed to get the facial hair working for my ghoul by using Face Ripper. I had just about given up hope before I tried tool--the few mustaches I did manage to get to work still clipped through the face quite a bit.
So what I ended up doing was using the Looks Menu mod to create a human version with as many burns as I could place on his face (I was resigned to the idea that he would have to be human at that point) and then I saved the preset.
I followed the instructions of Face Ripper, but then remembered that I had forgotten to switch the NPC's race to human in the CK. The game was loading at that point, so I just decided to see what happened. Much to my surprise and joy, I found a ghoul with all the customized facial geometry (minus the burns I think--hard to tell with the ghoul skin), hair and--most importantly--the much desired mustache standing before me.
However, after gazing at him for a long while and wondering why he looks so different from other ghouls, it finally hit me--he still has a nose! 
It's hard to tell with the ghoul skin. He sort of looks like he has had a severe injury. Like a chunk of the skin is missing, but his nose is still intact. I have been testing the mod out over the last few days, and I honestly think that his nose is not detracting from his status as a ghoul at all. Plus I came across some of the "talking heads" artwork from a spin-off/unofficial remake of Fallout 2. There are at least two ghoul characters in it who still have noses, and they look fine, so I have decided to keep my ghoul's appearance as it is, nose and all. 
Edited by Lollia, 08 May 2022 - 06:19 pm.