The motor is located in the bottom of the panel located just behind the door. It is covered in plastic, but there is a small access panel through which you may be able to disconnect it.
There are also sensor switches in the beginning of the tracks, where they end at the windshield. These are used to tell the mechanism the belt has reached the end of its travel. I don't know if they can help you in your goal, however.
Personally, I have always liked the automatic belts. Most people do not.
They do tend to make a lot of noise when not greased, but I have not found an effective method for greasing them with a thick lubricant.