afaik mplayer can play back this horrible reject of a media format, and they have a converter app called mencoder (I think), which can convert pretty much anything that mplayer itself can play. So you could drop the rm file into mencoder
somehow, and decompress it to wav.
That is, given that mplayer can process your particular rm file (there are fifty billion different versions of rm files at the very least), and if you can find your way in the incredible labyrinth of a documentation that explains how to use the app. As it is commandline only.
Worth a try at the very least. Heres their homepage:
http://www.mplayerhq.hu/
How ya doing, buddy?