Actually, the thrust reversers on most of the older airliners (707s, 27s, older 37s, most DC variants, etc.) work off of another set of levers attached to the throttles in the cockpit. Upon landing, while the engines are brought back to idle, this second set of levers rotates up, and as these reverser levers are pushed up and forward, they push the throttle levers back up to a certain setting for reverse thrust. The reverser clamshells are operated by these levers. On new airliners such as the Airbus, etc. I believe the reversers are actually computer controlled, as are all the other systems onboard. Maybe a set could be designed to servo operated off of another channel, or some type of microswitch activation of the servos that operate the reversers. Might be something for someone to pay around with and try.