I think you have to mount the motor. I remember it being a pain to align. Other than that it was not too bad as long as you have help lifting the bed.
I just got mine assembled tonight - Ill probably do a more in depth thread later, but I can quickly share how I mounted the motor as it was not problem.
1) After removing both the front and back panels, tip the entire base onto its front side (the pulley side of the motor is up)
2) Slide some spacer blocks between the ground (I laid down cardboard) and the motor - I found that three 3/4'' pieces of plywood scrap was perfect - they came to about 1/8'' below the motor (Picture 1).
3) Undo the two bolts holding the motor to the top of the cabinet. The motor will sink slightly and sit on your scrap base.
4) Slide/rotate motor on its handy plywood base over to the motor mounting bracket (Picture 2)
5) Well look at that - the holes are lined right up! Bolt away, no lifting required. (Picture 3)
As for getting the bed up onto the cabinet - piece of cake. My neighbor and I lifted it right up with no problems (and Im not the biggest guy in the world...or even on the block). Two reasonably strong people should have no problem getting that thing up there; IMHO a chainfall/hoist is definitely overkill unless you have no help.