So if you don't know how to do it, or just don't want to clean your whole map because you don't like one texture on a unit, here's how I did it. I used the rep_inf_arc_pack_blue in doing this, but I'll show you with the trooper skin.
1)First, delete the .tga that you don't want, rep_inf_trooper.tga, say if it's black and you want the old white back.
2)If you have a .tga editor, which you probably do, otherwise you most likely wouldn't be reading this, open it up, and find the white rep_inf_trooper.tga that you want to put back in the side. Convert it into a different format, I did the .jpg, though any format will work, but keep the name.
3)Then, reconvert it back into a .tga format, and put it back inot the file, replacing the one that you just deleted. What this does is make the texture a newly created .tga, with a newer creation date than the black one, so that the VisualMunge will read the rep_inf_trooper.tga, as opposed to ingnoring it as an unmoddified file.
This came in very handy for me earlier, where, instead of having to clean and remunge, or go and create a new .msh , I was able to fool the VM into thinking I had added something new.
I don't know if someone has already stated something to this effect, but I figured why not share the knowledge that I've gained with everyone, help others out who having been experienceing the same problems. Before I started reading the gametoast forums, I had to create a new dummy map everysingle time that I tried changing an old skin, which was a huge pain, and caused a lot of errors with mix-ups. I had to restart my entire side mod once because I munged the wrong side, and when I went to fix an error, I tampered with teh wrong side in the wrong dummy map. So this is a big help to me, easy and fast.
i think that you are what GT should be about. Learn stuff then help the more n00by people. nice one 
