Here are some quick FAQ about the 1st gen W-body keyless entry.
Q: Does your car have Keyless entry?
A: A couple easy ways to check if you have keyless entry is to look in your trunk by your attenna and see if you have this connector.
HereAnother way to check is to find your Service Parts Identification Label (ususally on the spare tire cover). Look on this label and if you find the RPO (Regular Production Options) Code "AUO" you have keyless entry.
Q: How do I program my keyless entry?
A: There is a connector in your trunk by your attenna. That connector is pictured
Here. To program it you simply ground that connector and keep it grounded. The door locks should lock and unlock to show the box is ready for programming. Then all you do is hit a button on your keyfob. If the car responds to the keyfob, press a button on the second keyfob (if you have one) and you're all done. Just be sure to un-ground the connector.
Here's a Video showing how to program the remotes!
Q: My keyless entry doesn't work. Why?
A: Many 1st gen W-body's had "cold" solder joints in the keyless boxes. Over time the connections crack and the box becomes inoperable. If you're good at soldering crack open the box and resolder all the joints.