Mod includes all 10 colors (taken from Decapre's mod) for Costume 3, and it works with USFIV Steam version.
I have tried this costume in slot 1, and it also works.
To use it in slot 1 you got to rename all files to change from CMY_03... to CMY_01...
I haven't tried it in any other slot, so no idea if it will work.

Drop the contents of the zip file inside your game folder at:
...\Steam\steamapps\common\Super Street Fighter IV - Arcade Edition\patch_ae2_tu1\battle\chara\CMY

If this folder doesn't exist, just create it.

The mod shouldn't overwrite any file, but make sure to have a backup of your original files before installing the mod.

Original mod from Cammy (not working on USFIV Steam version):
https://www.deviantart.com/siegfried129/art/Super-street-fighter-4-PC-Mad-Gear-Cammy-455009030

Original mod from Decapre (it works on USFIV Steam version):
https://www.deviantart.com/siegfried129/art/Ultra-street-fighter-4-PC-Mad-Gear-Decapre-477875604