No one has developed a proven method of transforming mdl files to x.
You could try
Fragmotion (this would be my bet). The guy who made it is extremely helpful and has a forum. He also seems to take feature requests and fix bugs that users find quite regularly.
You could also try Unwrap3d as Fred P suggested (not proved) but it is a bit expensive, and there doesn't seem to a support forum if you have troubles.
As a side note, this "comic book guy" type abuse wasn't warranted.
Out of the so called 37 topics not one answered this question. If anything they just confused the issue.
This guy was given a spray for no reason, which is stupid and simply lacks class.