by Boikat » Sun Nov 13, 2011 1:48 pm
You will need either Dxtbmp (freeware) or imagetool (I believe that's part of the SDK, but I believe it can be downloaded separately)
Then you will need a good graphics editor, like Paintshop pro, or Photoshop to edit the actual textures.

"I reject your reality, and substitute my own" Adam Savage, Mythbusters