Is there any way to integrate my I-phone 3G (for audio, it's already linked to the HFL) to my '07 TL-S so that it:

1. Doesn't require any permanent modifications to the car's wiring
2. Retains XM
3. Charges at the same time that it's plugged in
4. Allows steering wheel and/or touch screen functionality

I've searched, but I don't see an easy answer.

Thanks for any help!