Take a look at Anim8or: http://www.anim8or.com , if you want to d/l it click the 0.97 preview link on the left side (it's improved).
If you are now SURE that you know its characteristics and checked the file format (especially figures & sequences), keep reading:
The idea is to implement an editor in MH similar to the Pose editor, but this time with a timebar, so that it will produce sequences.
Then the sequences that are produced can be exported in an .an8 file, and then voila: you have motion.
Of course you have to learn about bones & weight painting in anim8or so that the seq.s produced will be flawless.
But I'll just leave the job to the pros (guess who, that's you
). Thanks in advance.