I think you can find pictures on the forum if you poke around some. As I recall they're using two linear actuators, pushing horizontally on the bottom end of the scissor lift tubes. One flaw in this system seems to be that if a hook catches or anything else restrains the top, the tubing bends pretty easily.
That's just my recollection though -- I have a manual top.
I've also seen non-SMB systems that used an airbag at each corner to do the lifting, which is an interesting idea.
1990 E-250 Sportsmobile w/ penthouse top, converted when new by SMB Texas.