Well, Google finds
this.
Combine it with an ID3 (I assume we're talking MP3) extraction/editing program and that should do it I suppose. You would need a shell script (In case Tom wants to ask, that's a fancy name for a batch file

) to glue it all together, though.
EDIT: This looks more promising:
http://www.cs.berkeley.edu/~zf/id3iconv/