added keyless entry to a 2000 cavalier from a wrecked 2004

I recently added a complete wiring hareness and 4 doors with pwr windows and locks from a wrecked 2004 to a 2000 cavalier that did not have either factory option. I tried to have the keyless remotes programmed to operate the system at a dealer ship and was told that the BCM body control module was locked and a keyless system could not be installed suing the cars original 2000 bcm. Qoestion, in order to get this system running do i need a bcm from a car that had been factory programmed for a keyless system, and if I replace the existing BCM what features may be lost or need programming ie cd radio?