You'd need to change the mesh itself, due to the new MTF facing the ground, and you'd need to change some code in the files so the animations are timed. Well, I recently discovered (and by recently I mean today) the little tidbit that the new MTF model faces downwards on its face by using a program...

Okay, managed to figure out how to get the model textured.
He's still drifting along on his back, however.
Any help?

Okay, I followed the steps provided in the last reply. However, I'm at least 90% sure that I did something wrong. I managed to port the model over, but everything else is broken. The helmet IS textured, but it uses the zombie helmet texture whilst also adding a yellow visor on top, everything below ...