The most important issues are:
1) Can the BoJ control the JGB (the Japanese Government Bond) market?
Bass and Koo don't seem to think so but Pritchard comes with good examples to show that this is indeed possible.
2) Once unleashed, can the BoJ control inflation from spiralling out of control and keep it at 2-4%, a nice pace at which real debt burdens will dissolve slowly like snow melts in a pleasant spring sun?
That's a trickier question..