An electrician's bit and working from above might be the fastest. Miserable conditions up there. Vertical clearances are as low as 8". Additionally, half of the kitchen has a double roof over the ceiling. There has been an addition done and instead of removing the old roof they simply build another one above. W(Out West this method is called a 'California Roof').

Anyway, drilling from above and accurately measuring and diagramming from the attic should save a lot of time.

Thanks, Ivan Vegvary