The receiver for the factory keyless entry is mounted on the rear package shelf (rear dash). It's underneath the carpet between the 3rd brake light and back seat, inside the car.
The programming terminal is located on the left hand side of the trunk opening in the wiring harness. When you short the 2 pins together it should cycle the locks and then the trunk solenoid.
If you can get that much to work then you may be able to get it to work with a new remote. My remotes are totally busted or I would send them to you. Maybe you could find someone in your area that has a remote and try it.
But all in all, an aftermarket unit will be a lot less hassle. Make sure if you get one that it sends positive pulses. Thats how you trigger the locks and trunk release on a caprice.
If you have anymore questions PM me and I'll try to help you out.