Hi aprejean & Peter,
Since "mush" is a post process to the deformation, I dont think its possible to convert it to skin weights in a simple process.
This task require teaching each joint about the best possible weight of vertices.
Not sure, but Jason Osipa may did something similar.
I think he was teaching the joints its weight from blend shapes (in other words : converting blend shapes to skin joints)
Peter, the mic with u now.