I used something like these and a couple relays added to my existing alarm. pretty easy and inexpensive if you do it yourself.
http://cgi.ebay.com/1-PAIR-OF-POWER-...item33594101ca

 

Andrew.. those are nice and would make for a clean and simple install. Also if you need to replace the entire door latch these would be perfect.

However the actuators on these 300.00 are exactly the same thing as whats in the cheaper universal keyless entry kits. Take your car into any shop to have keyless entry installed and these universal kits are what you'll get.

Just wanted to point that out as some people may not realize. The 20 to 40 dollar kits will perform just as well and just as long. Your mainly paying for the new door latch assembly there.

 

You might also want to add a trunk release at the same time. I added electric door locks, alarm, as well as a trunk release to the 65 coupe I built for the wife. I bought the trunk release with the chrome handle in the drivers side and wired it into the alarm. It sure is nice when you walk up the to car to unlock doors or have the trunk swing open to put something in the trunk.