I'm not sure about the Controlmap_Custom, but it screws my custom Controlmap so i suppose it could lead to problems
And you can't change "hard coded"(sort of) keys in that way
You can find this file in the archive Skyrim - Interface.bsa
I just extracted from there, it's fresh new, i only switched the Mouse1 and Mouse2 scancodes (0x0 and 0x1 in the third column)
For simple editing and complete understanding, extract from "Skyrim - Interface.bsa" all the txt files in the folder
\Interface\Controls\pc\
gamepad.txt
keyboard_*language*.txt (keyboard language layout)
mouse.txt
controlmap.txt
The file you need to edit it's Controlmap.txt . The other files are useful to know the key codes mapping (editing these has no effect) .
You can also assign combinations of keys with "+" (example 0x1000+0x4000 = controller LB+X)
I suggest editing with Notepad++, or other editor, instead of windows notepad, it's simpler to adjust the columns with tabulations and without "line wrap".
On the top in the comments, it says that 1st 2nd 3rd....etc are the columns of the "table".
// 1st field: User event name. DO NOT ALTER! This field is used to ID events in the code
as it says, don't change this
// 2nd: Keyboard key ID that will proc this event. A value of 0xff means the event is unmapped for this device.
-->(refer to keyboard_*language*.txt)
// 3rd: Mouse button ID that will proc this event.
--> (refer to mouse.txt)
// 4th: Gamepad button ID that will proc this event.
--> (refer to gamepad.txt)
// 5th: If set to 1, this event can be remapped to a keyboard key
// 6th: If set to 1, this event can be remapped to a mouse button
// 7th: If set to 1, this event can be remapped to a gamepad button
-->allows to remap from the main menu
// 8th (Optional): User event binary flag. Used to group together related user events, like "Movement" or
// "Menu", so they can be toggled on and off together
--> flags for certain purposes, example the flag 0x801 from "Strafe Left" will prevent you to move the text cursor on left while in inputboxes everytime you click A
That's pretty much it, it's not that difficult, it only takes a bit of time to adjust as your likings