I put a little more thought into this and I don't see why this wouldn't work. All you would need to do is make sure you have 120 volts (hot and a neutral) in the box you want to put the CBD-AD. You will probably have to take out the existing switch and wire nut one of the travelers going to the 3/way switch to make it constant 120 volts in the other box. All the programming is done in the PMC2 so this should work. Both gateways talk to the same processor.