I stumbles across this 15 page thread and read it all with excitement. Very interesting and a good idea. I have to throw this out there though: anyone looking to do this should have the rear derailleur hanger alignment checked at a bike shop or buy the park tool (Park DAG-1) to do it yourself. Being out a couple millimeters can make a big difference in shifting when putting the leg to it, could get ugly when adding in the torque of the motor. And make sure the low limit screw is adjusted so the derailleur doesn't meet the spokes and lunch the wheel. And don't just put on a new chain, have the chain checked for stretch with the propper checker (Park CC-2) or just put a whole new drivetrain on. New tolerance chain on old cogs means skipping and trouble. Not as bad on older mountain bikes with 6 or 7 cogs in the rear but an 8 or 9 should definitely be checked.
And did I read those last few posts right, you will be able to lean a bike over, clutch lever out, and use the crank arm like a kick starter?