Yes, this is years late, but I'm just back from YAPC::NA and back in a Perl state of mind.
I started out saying that I wanted a pure Perl implementation. The description you link to says.
in reply to Re: The Exponentiation of (not-so) Large Primes
in thread The Exponentiation of (not-so) Large Primes
It uses dc, an arbritrary precision arithmetic package that ships with most UNIX systems.
That isn't quite what I was hoping for. And, y'know? Those two-line implementations of things are exactly why people have a bad view of Perl. Yes, it's wonderful and cool that such a small implementation exists. But I was hoping to put this together for a presentation for my LUG, and having code that someone who isn't a full-on Perl guru can look at and understand is a good thing when you're trying to teach it.
I don't want to be harsh -- you were trying to help -- and I do suck for abandoning this thought for four years. It's just that the cool 2-line implementation that calls dc isn't what I need.