i don't know why i didn't think of this earlier; UE3 is still a pretty moddable platform, are you going to be supporting any sort of mods/mutators, and if so to what extent?
I wonder if it would be much work to support custom textures for the player character? Maybe you could check a certain folder and if theres a texture you replace the ingame texture with it. There are tools to do that and you can brute force it as modder but it would be easier for the not so mod savvy players. Just an idea.
UE's mod system should work in a similar fashion to SupCom's. then again, UT2004 simply let players drop a handful of files into the right places and it would add a character with a new texture and the same mesh and bone structure.