As of 3.0 Muster supports MR for maya. To do this, it calls maya with a few extra commands to change the start and end frames. One thing I discovered is that you need to make sure that you use the frame range "DerivedfromMaya" rather than forcing it in the MR section.
3.0 muster fixes quite a few problems, but I still have seen some issues with zombie processes getting left behind, consuming RAM. Not all the time though.... I now even have it working on the Mac.
-MD