Not bad! Thanks for your suggestion! I gave that a go; unfortunately it looks like Parse::Lex depends on those syms being there, and I hacked at it for quite some time without convincing it that they should be elsewhere. (I'd probably have to study it for some time longer, but the long and short of it is that I'd be monkeypatching a lot more than just exportTo(), so I'll leave it.)
For now I'll just leave my module non-reentrant, until I work out another way, or maybe switch lexer generator.