I think it's necessary to try to clear this up, making the texture transparent does not "allow the team color to shine through." It does one of two things, make that part of the model transparent, or make that part of the model team colored.
Like End said, Blizzard models already have that set, but you can change it without too much difficulty. If you want to learn how to change it from team color to transparent or vice versa I will move this thread for you.
If you want to make team color/transparency show on the model, all you have to do is make sure your texture has a transparent background and erase whatever you want to be alphaed, then save as a .tga and export to blp.