#KeeJay :
I've made a little mistake - it's TypeID, not SuperID
It's easy if you know basics. But I think that you don't know them, so I'll try to explain it as close I can.
1. Choosing proper texture
First, you need to check how mesh's .tex file is written. Let's use mine latest rim as example:
And the default_gray.png is a plain gray color texture (diffuse), and it's TypeID is 0x00000020.
You need to guess what texture is the proper one - you can check them in textures folder.
Some modders leave .tex files untouched, and you need to take the SuperID from RPK.