I learned today how to do it. I haven't done it yet, but I will in the near future.

I was getting my V1 hardwired at a local high-end car stereo shop. I trust them more than myself to do stuff like that.
Anyway, I asked them about the Porsche system on '02's with Bose and the lack of the Aux input for MP3 players, etc.
He told me that they could do that no problem. They did one with a Satellite and MP3 player hookup.

It's a work-around. They basically hook a relay or switch (not sure of terminology) into the CD player hookup.
The stereo always thinks it's playing a CD, but a switch on the dash controls what's actually being fed into it. So, the head unit will always say "CD", but your switch can make it feed in either the CD, the MP3 player, or whatever else you hook up to it. There's no loss of quality, and it's all digital.

I'm going to do this very soon and I'll post results.


[If this was already known to the board, my apologies, but I just learned it, so I thought I'd share]

 

Unfortunately, that won't work for '03+ cars with the MOST bus, since the components are connected with fiber optic cable.