Yes you can.
Example:
\f12011\frontend\b_driver_jenson_button.pssg
Use Ryder tool to open pssg file, extract "jenson_button.dds" and The Compressonator to extract .dds to .tga file and edit the photo or replace. Reinsert with same tools. Done...
Thats iof you use Paint Shop pro, I think photoshop can open .dds files, but I am not sure. I use PSP 9.