I have the Dension kit for the CDR-220. It is NOT an FM kit. It plugs into the CD changer input on the back of the stereo. Lets just say it works very well when it works. The installation instructions where horrible, and assumed that you knew to hook some miscellaneous wires up to random stuff. When I first got it in the mail half of the parts were missing and they had to send a second shipment with the rest of the stuff. After I got it all set, it works great. The radio buttons control the iPod and the disc buttons select which play list is being played. It was also fairly expensive. So if you got some extra cash and have mad car stereo install skills (which I don’t) check it out.
http://www.densionusa.com/main.htm
PS: I didnt have the CD changer to start with and I dont like FM transmitters