I use a soundgate device that connects to the XM or Sirius (in my case i replaced it with sirius) harness and if you seek up 3 and down 1 it turns off the sirius and plays the aux input (ipod), then if I seek up 1 and down 1 then it goes back to sirius. It works great so far. I have an 06. I tried the USa Spec and another one, but neither seemed to like the fact that I had the 6 disc bose with onstar, XM, and rear seat audio. So the soundgate finally worked. Bought it from a local vendor in Campbell for around $90 if I remember correctly.