Had one professionally installed years ago. I'd remove it except the way it's wired in is so complex I'm afraid to touch it. I want to remove it because it's coupled with a remote starter, and now that the car is a stick I want it gone just in case
I did a search and found some info, nothing complete enough to link, there was a guy that used a ford keyless system from a sn95, most used aftermarket systems with mixed reviews, talk to a stereo shop that does installs for alarms or search online, major alarm systems have instuction sheets to look at.
I have a Viper alarm system on my 92. I installed it myself. The module has a separate wire that can be connected to the power door lock system. When you hit the disarm button on the Viper key fob, it turns off the alarm and unlocks the doors. If you manually lock the doors once in the car, after your drive, when you turn off the ignition, the doors automatically unlock. Also, when you get out of the car and hit the key fob to arm the alarm, the doors lock as well.