i just bought a 2007 Carrera S equipped with an after market Sirius radio. What buttons do I hit to activate it to get the music to play through the stereo.
Is there an auxiliary button?

 

Most aftermkt kits will modulate thru a designated FM station though there were some other options out there (i.e. to clone it as a CD/Multi-disc changer, etc.). I'd first start by turning on the Sirius radio and then scan the FM spectrum via the head unit. If you don't find there, try cycling thru the AM/FM buttons a number of times and the CD button on the head unit. Someone here may have a similar set up so a picture would help too.

Good luck

 

If it's a wireless setup, and the previous owner was using it you should be able to just turn on the sirius unit and then go through the preset FM satins on your PCM until you hear the Sirius unit playing. If that doesn't work the official instructions for setting up a station are as follows...." Select an FM station onyou PCM that isn't being used. Go to sirius.con to find available stations in your area. Tiurn on the sirius unit and holdvthe FM preset button for 2 seconds to access the FM preset list. Then choose FM preset 1-5 to program and match the same FM station as your car radio. "
Or you can probably get the instructions on lineat sirius.com.