You could also try and get your electronics department to wire you one up. They are rather simple - the diagrams are available on the web.
Basically, the more "advanced" have a two pole switch - the top latches, the bottom is momentary. Press up, the "Standby" light comes on (if you have the extra money, you can change the circuit slightly so that the SB light will flash at both ends until acknowledged, when they go solid), then when you press down, standby comes off, and go goes green. Being momentary, when you release the cue light switch, it turns off automatically.
When you are used to the cue light system in a venue (as I am sure this SM is), your use of them will be based solely on muscle memory, you know exactly where each switch is, and your hands can do it without watching.