The attached pic shown the CD extansion cable you will need. It should plug in to your radio module under the spare tire on one end (white plug) and into your 6 pin connector on the back of the CD changer on the other end. Disconnect the single blk coax cable from your CD changer...you will no longer need it.
There is a good writeup under the stereo section with pics. Here's the link...
Sirius install with NAV ...