If it's any help to you, when I did the keyless in my 91 coupe I had a lot of trouble finding the door lock wires. I tested every one that matched the colors they were supposed to be in the driver kick panel and none of them were lock wires.
I finally realized that the wires were tucked way up under the dash but by removing the driver's side dash speaker grill I was able to get at the wires much more easily. They are taped and I think connected by a tab or two but you can pull them out a bit carefully and then make your lock/unlock connections there. Still not the most room to work but much better than trying to work with them up under the dash.
I believe most keyless entry systems support 5-wire lock systems so you should be able to get it working without a separate set of relays. Oh and one other note, my lock/unlock wires were the opposite of the color codes I found online so be sure to test them to know for sure which are which