all right, we'll say this for the last time, no one will ever get a factory CD changer, to work with an aftermarket headunit, plain and simple. do you really think that your cd changer in your 06 sierra (full size chevy) is really much different than an 04 esclade (full size chevy)or have you not really been reading the whole thread.
you can also kiss the rear seat controls good by, i have got a few to work with aftermarket radios, but it had to use the steering wheel controls input (meaning that you can not also have the steering wheel controls working at the same time) its one or the other.
now you actually have some good news, with most of the chevy overheads its pretty simple to retain them, especially if it is one of the Panasonic built units.
for this you will need to run a set of AV cables back to the over head system from the AVIC's AV out plugs, then you will need to disassamble the over head and find the AV inputs, cut the wires running to the back of the board with the RCA connectors and cut off the ends of the newely ran RCA cables and then solder them together (if you dont know how to do this, then take it to someone that does)
also with most of the chevys i have done, you can run another set of RCA's from the overhead back up to the AVIC's AV input and tap into the video lines comming out the the factory DVD player as it goes into the monitor so that somebody can also use the rear DVD player and you can select it as a source from the front and watch it up there.
there you go, now you can control a video for the kids in the back, or let the adults in the back handle playing a movie for you.