The car needs to be connected to a GM diagnostic scan/programmer called a Tech-II. ($4,000+ in case you get ideas....) Dealer job. If you bought the car from a GM dealer they should do the name change at no charge. Otherwise they'll charge you some portion of a labor hour.
While you're pushing DIC buttons, go to the top of these forum pages and learn how to pull and interpret DTC's (Diagnostic Trouble Codes) and also go to the sticker on the underside of the spare tire cover to find the RPO (Regular Production Option) codes for what's actually in
your car. Download the RPO list from here or go to
www.cadillacfaq.com/rpo/index.php and create your own printout.