Bluetooth will work (may have occasional hiccups sending data to the IPC) you'll have to hack the wiring in the car but the onstar will never operate as designed. This has been covered numerous times.
Dealers DO NOT have the ability to reprogram a VCIM only to run a config file which changes NOTHING in the flash/OS/operations ect in fact all it does in this instance is set the car up for the wrong BCM calibration LOL