I am working on the same problem, while creating a intervalometer with an arduino is pretty straight forward, the functionality of the bulb ramping of Magic Lantern is worth letting the camera control the slider. I'm using a belt drive stepper motor to move my slider and this seems to produce some vibration, so I'm going to use the ML bulb ramping function to do a Move Shoot Move arrangement. This will minimize image blur since the shutter is only open when the camera is stationary. Does anyone have a pin out of the hot shoe for a Canon EOS 60d? Are you sure the pin-outs are optoisolated from the camera. I don't care that much about my Arduino board as long as it doesn't kill my camera.