keyless entry system problem.... HELP

Hey all, I got a keyless entry system for my fiance's 92 mercury grand marquis in the mail about a week ago. I am lost as to how to wire it up. I mounted it, gave it a constant 12+ and a gorund, and I programed the remotes that it came with. I then used a test light to see if it works, (took negative wire from unit and +12 test wire) and it does (button pused on remote and light goes on). The only wires that I have left to wire up (besides the constant + and the ground I already did) are a - signal wire for the lock and a - signal wire for the unlock. This is a very basic system and I dont know how it hooks up. I wired them temporarily to corrosponding - wires in the door lock switch unit thing (actually in the door arm rest) and nothing. I dont know how sending additional - current to an already - line will make anything happen anyway. I hope that I make some sense and that someone can help me.

Thanks!