I'm back on this again, sorry...
Zagatoes & catman. :are you both talking about disconnecting the CD changer from the NIT, and using the CD changer input? So on the dash interface you select CD changer and it picks up on whatever your device is playing?
OR: Do you mean connecting a device to the CD changer, so the changer thinks it is reading a CD? Then you just pick that particular CD using the changer controls, and bobs yer uncle?
Or have I got these wrong completely, and you aren't using the CD changer input at all, and are using the other in-car CD player (the one that houses the sat nav CD?