http://www.xcarlink.co.uk/product.php?productid=55&cat=15&page=1
I bought this the other day and it works a treat!
My cd player is the one that has the option of putting the 6 disk changer on. This adapter just clips into the socket where the 6 disk changer would have gone. You can control the ipod off the steering wheel controls, you can change playlists, the volume, skip tracks, fast forward and rewind.
Hope this helps