I've regularly tried to find a solution to this, every few months for the last two or three years, one of the last things holding me back from wiping OS X. Posting here a) in case anyone else on the list is interested and b) to have it recorded in the archive for other people's web searching pleasure.
Imagine the ixquick-fu needed to find this:
https://code.google.com/p/itunes-to-rhythmbox-ratings/issues/detail?id=1
Here's the link to the crucial working revision 0.9.0, not the widely-accessible bust 0.8.1 from that page:
