recently I modded my brothers radio in his BMW and my radio in my SAAB to accept ipod. the procedures were almost identicle, and the pinout of the cassette was the same iirc.
http://jcrowell.info/bmw-aux-in.html
I posted this to be published in the magazine, but I figure that it probably wont be, so i figured that I would try to at least let a few people know about it .

To the editors of MAKE: I love your magazine and store (my make: daisy is what I use instead of an ipod in the car!) And would be very honored if you do decide to publish my story