Related to the OP's question and what you've said, I've got a few quick questions of my own.
I'm looking to mod some of the graphics and I already downloaded the .dds plugin for photoshop, but I'm useless at anything involving scripts/programming. I did take a quick look through the documentation, but it was a little overwhelming. But I'm not looking to mess with any of programming/scripting elements right now anyway, I just wanna change how it looks.
So I assume I can just take the default UI, copy and rename the folder and edit the graphics and just save them under the original filenames, and it should work ok? As long as I don't start messing with things like the dimensions and stuff?