lets see... in 5 hours, we've wondered, mused, guessed, and thought our way through the theory of a FWD into AWD swap
Take one front drive donor, rape it of the engine, transaxle and front hubs, and find another rear diff and side shafts from another donor RWD car.
take one rear drive victim and apply front hubs from fwd donor and drop engine in rotated 90 degrees. rip the diff apart in the transaxle and fit a modified drive shaft and 1:1 gears, and make a little housing for a hacksawed VLSD.
weld, pry bolt glue and otherwise fasten all bits together. Finally, ensure your life insurance is up to date and take a test drive...