Help with '97 Remote

So I'm buying a 97 Civic with an aftermarket radio. I understand that the OEM radio actually contained the reciever for the remotes and that to program new remotes you must use the buttons on the OEM radio... Supposedly there is a special jumper wire harness that must be used for aftermarket radios if one is to use the remotes.

So fundamentally, I'm trying to find out how this works... How can I tell if the aftermarket radio has this proper harness connections... How does one go about programming the remotes now that the OEM radio is no longer installed... etc. etc.

Someone please advise!

Thanks,
DB