Right now I'm working on a little project to run the GE relays off a PLC. It implements a few simple functions, like allowing the use maintained-contact switches (including photocontrols) or single pushbuttons in place of the system's standard double-throw switches. It will also allow master control of groups of relays, with override of individual circuits.

I haven't played with PLCs before, so the project has been a great learning experience - and a lot of fun. This is the PLC I'm using: Click PLC.