Looks like positive leads is all you need to bother with. The ground wires should be left alone.
I expect you'll need only one relay. In many cars, the system will unlock only the driver's door on the first press & then unlock all doors with the second. In my 1999, all of my doors unlock with the first press of the button (I installed my keyless entry too).
I could have worked it different by hooking up only my driver's door lock to the lock circuit of the keyless entry system, then rigging the main lock wiring to the trunk open lead, thus opening all the other locks on the second press of the button. (hmmm, may do that).
