1990 STE Keyless Entry Questions

The remote that I got with the car wasn't working. I replaced battery but no luck. I guess it was dead for too long.
1.How do you reprogram the remote ?
2.Can I add a remote that did not originally come with the car? I've seen a few on ebay that look like mine but I don't know if they will work.

Any help would be greatly appreciated!!!!

Check out the link below for some info that might work with your car. My keyless entry stopped working and it turned out to be the receiver module. Got one from a early 90s Blazer at a salvage yard for $10. As for remotes, hard telling. My original remote with an FCC ID of abo0103t worked with the Blazer receiver but I also got one off of ebay with an ID of abo0104t and it worked too.

http://www.automotiveforums.com/vbulletin/t119107.html

This is a common problem with the GEN I W-body cars.

Check out this link: http://www.w-body.com/service/keyless-entry.html