What gauge material? If it's anything heavier than 26, for just a few
sheets I'd go w/ the Sawzall metal blade if it's in place already.
I've heard of the other "trick" but no experience w/ trying it. I
might try one on the ground to see what works. Any way to stay on the
roof and work from the top instead of off the ladder?


Because it's corrogated, there's no easy way to keep the sawsall
grounded against the metal while cutting, which means that its
going to be really hard to control the beast against it's
reciprocating motion. A light circular saw may be
easier to control in this application.