replacing OEM radio\cd with upgrade OED radio/cd/cass in a 2002 Malibu

I have a 2002 malibu with the OEM AM/FM CD player with RDS. I can pick up the upgrade OEM unit, which adds a CD player to the mix. Can I just yank the old one and put this in it's place without screwing around with codes and the car computer? If not, is the necessary code/computer dance doable DIY, or is a dealer needed???