Click for install

A couple quick comments:

The FM Modulator method of getting the music from the harman/kardon works but the sound quality is poor
The factory head unit does not provide for auxiliary inputs, so you can only use the FM Modulator
If you use the direct connect FM Modulator, you will need Euro to US converters for both ends of the antenna wire

My write-up above takes you through what I did including wiring.

With the harman/kardon plugged directly into the AUX inputs of my NEW head unit, the sound is great, power from the car charges and powers the iPod, and the heads-up control is very useful.

You can get a great deal on the unit right now.