Try doing a use locale (); and a use utf8 ();, then calling (locale|utf8)::(un?)import as needed. Since they both work by setting $^H, and $^H has magicly strange scope, you may have to play around a bit with exactly where you call them. I should suspect the correct answer is "as early as possible", but I'm not sure.

Try reading utf8.pm and locale.pm, and perlvar for more on the scoping of $^H. On second look, you might have to put the calls to utf8/locale inside BEGIN, which would rather suck, because it would require you to do your option parsing there.