As far as I am aware there is only one way to convert live rm streams to other formats and thats using Total Recorder as that records whatever is sent to the sound card regardless of the source. This makes it probably the only way to convert a stream from a protected source (and is how I got the prodigy set!).
Get it here (and make sure you read my warning below first!!!!):
http://www.highcriteria.com/productfr.htm
You need to set it up in it's options to record directly from the sound card to make it work.
TBH It's a lot more complicated than streambox ripper which is the best way of converting .rm files if you have the actual files and are not streaming them live, just drag and drop the .rm file onto the streambox window and it'll do the rest!
********************
** SERIOUS WARNING **
********************
Whilst the package I mentioned above, Total Recorder, does the business as far as recording streams that would otherwise be impossible to grab - it fecks up your system no end! Video's won't play, games won't have sound, winAMP will claim something else is using the soundcard and resetting the computer doesn't fix it!!!!!!
The only way I could sort it was by uninstalling Total Recorder and resetting the machine! Only use this software as an absolute last resort!!!!!