I was looking to do the same thing. I've ordered this adapter and waiting for delivery:
http://www.cardomain.com/item/USSPA11CHR?vq_id=none
It has the same functionality, i.e. pretends to be a CD changer and allows to control iPod from the factory radio. You have to compose 5 playlists and they will be seen as CDs in the CD changer. It will not allow to display the song names though. Costs about 110$.