Can 96 Sable be programmed for remote?

I bought my grandparents 96 mercury sable and it doesn't have keyless entry. Can keyless entry be added without going to a dealership? Can I just by a remote off ebay and program it on my own? Thank you.

I bought a remote start module with the keyless entry last weekend and based on the instructions, I should be able to use that as my keyless entry remote.

i believe every sable came with keyless entry and your grandparents just lost the remote, therefore you should be able to program it.