Arragonis: Oops. Didn't see your question. Yeah, it would have to force the motor to turn over too. I think anyway. I'm yet to see anyone actually do it this way so it's all pretty much theories right now.
Jerry: AC-12/ whatever controller comes with it.
Shadetree: Yup! It's possible, although I don't know how much my trans would like it. They're notoriously picky. I guess I could swap with a FWD trans but they are hard to find.
Here's a picture of the subaru AWD Set up:
The engine and transmission are located as if they were in a RWD car. The front differential, transmission, and rear transfer case are all a single unit. Then a regular drive shaft and rear differential (R160) to the back.