A ) have a hacked DirecTiVo (one of the older, non-DirecTV branded ones, the R10 one is unhackable last I checked...)
B ) have a way to take the TyStream (TiVo's proprietary format) off the DirecTiVo and place it onto another computer
C ) have a program to re-encode the TyStream into an mpeg stream then another program to rip out the audio from the mpeg stream and encode it into a <insert format of choice here> file
So in essence, yes it is possible...
If what your really asking is a step-by-step, infalliable, easy to use instruction manual on how to setup and do this, tough shit. I don't have the time to write one..and I don't have the ambition or monetary incentive to do so either. And on top of everything else...you have to be pretty Linux saavy to setup half this stuff...so it isn't the easiest of things to do...let alone script it so it's done automatically. If you want the mp3's that bad, may I suggest Audible?!??
True, but if you record off XM Online it sounds a lot better, and it's in stereo too. Plus, you can get it faster than waiting for someone to put it on the newsgroup and then for someone to download it and torrent it.