Has anyone done any texture swapping on Damnation?

[dalecooper]

I'm wondering which textures are the most prevalent, and if anyone's had any luck changing them out for other ones. I was able to do the sky and cloud textures easily, but I tried swapping just one of the covie textures (Generic Metal) and it coughed up a lung when I launched the map. I'd like to redo all the major surfaces just for fun.