Game control

I found a mod (Ghost-in-the-Shell) that makes everyone look like some kind of ghost (similar to that dead Nali in one of the original Unreal maps). Anyway, I was wondering if someone knows a way to make individual players/bots appear this way at the command-line level without affecting any of the other bots or players?

I'm trying to make an RTMS movie, and would like one of the characters to appear ghost-like. Invisibility is too transparent, and the mod I mentioned affects everybody at once.