I just did it on my 05 Yukon XL w Bose system
All you need is a GMOS-04 interface to retain your onstar and to turn on the bose amp and dvd system. The headphones and player will work as normal.
Now if you want the Video and Audio out to your headunit thats a different story and it is also doable but requires finding the correct leads off the dvd player and running rca's from your headliner to your headunit/brain. I also did this and the leads for my unit were darkk blue for video and brown and black for my audio along with a common ground going to a shielded wire that is pretty ea
