Well, I drew up something in ms paint for what we were planning to do, as it seems to be the easiest way to move a scissor lift, as all the forces are vertical and you can collapse it very far.
http://img245.imageshack.us/img245/1225/liftqp7.jpg
obviously not to scale and sorry, I'm on a laptop. haha.
... but this extended is about an 18 inch stroke, which is giving us problems. We plan to have one end on top and one end on bottom fixed, with the other two on slides. Obviously supported very well.