I have a Lexus IS300 with Navi, i purchased a DICE Car Integration Kit from www.incaripod.com, it's a fantastic piece of equiptment.
You can control in from both Steering Wheel and Radio, which also lists artists and tracks, and the sound quality is crystal clear.
Connects straight into the CD port in the back of the radio, so not too difficult to fit
Does anyone else have this kit or any simular? because it's well recommended from myself.