Yes, using an ESC is possible or even this (http://www.dimensionengineering.com/PicoSwitch.htm) -- it will cost extra however. What I meant by using a continuous servo (http://www.acroname.com/robotics/inf...ontinuous.html) was replacing the turret rotation mechanism with the servo. Remove the final gear of the turret rotation mechanism and connect it to the output shaft of the modified servo. For gun elevation, just use a control rod from the gun to the arm of the servo controlled by your (ratcheted) throttle stick.