05 Suburban with NAV and DVD entertainment.

I just picked up my new Suburban and love it, but when I ordered it I was told by the sales person that the new NAV units with the touch screen was also a CD changer and as most of you probably already know it's not. The seperate CD changer that was available in earlier models with NAV is no longer available from the factory, but I was wondering if maybe I could add one. The only problem I see is the DVD player in the rear, does it use the CD changer input and can I have both? Has anyone run into this yet?