There a lot of different ways to wire in an iPod. I just put in a powered dock connector that works great for me (check my sig.), but I control the music through the iPod. You can also just put in a universal audio jack.
I am not sure if there is a way to be able to control the iPod throught the Porsche stereo/nav, but it can be done with an aftermarket radio/nav.
Hope this Helps!
