96 Deville Keyless Entry Remote/fob Programming

Hi, I just bought a used spare Cadillac remote key fob for my '96 Deville off Ebay. It has the same GM and FCC ID numbers as my original remote, and both units are a number 2 remote.

How do I go about getting the new remote programmed to work with the car? And roughly how much should this procedure cost?

Thank you.

There's procedures in the service manual on how to do it, or a dealer can. Not sure on the cost though.