Nice. Creative solution to it, especially since you based it on what you have out there. Looking at the need here are a couple quick ideas for others:
1) Using a Z-Wave or ZigBee relay to directly switch power for the lock.
2) Using a curtain or other motorized ZigBee or Z-Wave controller (Monoprice used to have a bunch cheap, have not looked lately) in order to power a solenoid to act as the lock's bolt.