I am interested in adding power door locks too so I opened up one of the rear doors to have a look. Nissan did not pre-wire for the power door locks so wires will have to be run through the boots that carry the speaker wires. Most importantly, the lock mechanism is totally enclosed in a plastic shell and is operated by sheathed cables. This is evident when looking at Courtesy Nissan's online catalog. It may be quite difficult to find a way to link the pushrods from the Electric Life actuators into the lock mechanism.
Looking in Courtesy Nissan's online catalog, it appears that there are two different lock mechanisms for the front doors, one without power and one with the actuator integrated into it. Similarly, there are two different lock mechanisms for the rear doors, one without power and one to go with an actuator. I think that it all comes to about $500-$600. Then there is the issue of finding appropriate connectors.
It appears that the best way may be to find a vehicle in a scrap yard and remove the door lock mechanisms, switches and part of the wiring harnesses.
Any other ideas?
Phil