Right -- the center off position of the switch is the only way to stop the motor. It also ensures that the motor cannot be reversed before being stopped. When the switch is thrown one way, the hot run wire is energized and the start wires are polarized one way; when thrown in the opposite direction, the hot run wire is again energized but the start wires are polarized the opposite way, which causes the motor to start in the other rotation. All switching is of the 120V operating current.

I'm thinking of using a couple of X10 low-voltage relays to receive Forward and Reverse commands. A high-voltage DPDT relay controls the polarity of the start wires and an SPDT relay controls current to the DPDT and the run wire. The DPDT is set for normal Forward; when tripped by the X10 Reverse relay it switches to the Reverse configuration. Somehow I need to get both X10 relays to trip the SPDT relay so current will be supplied when either X10 gets an "ON" command, but I haven't figured that out yet. Another problem is that it would be possible to trip the DPDT to Reverse while it is already operating in Open.

For auto shutoff, I was thinking of using the Leviton Dry Contract Transmitter momentary version and a two closure magnets on the frame with one traveling magnet on the skylight. The Leviton can be configured to send an "OFF" command on closure and no command on opening, so it can send the appropriate "OFF" when the skylight reaches either travel limit.