You mean by the graphics?
There are all tools for extract the graphic file(.dds) packed in TDB files i guess and also to to pack them back
After Extract use Photoshop with .dds plugin
Then Use your imagination and make what you want then pack them back
and then put then in the client , if all done correctly you will have new graphic or IF I REMEMBER CORRECTLY THE YOU WILL "client corrupted"
I use to these 3-4 year back but i am not good with Photoshop
and if you are good enough then you can use the same tools and method to change the looks of weapons etc ,
All the UV map are the is the client file
You need to dig deep in and invest time