Use the various search options ( http://search.cpan.org,...) and find code to generate permutation as you want, and generate a list of words (I believe there is an example in Higher Order Perl).

Then give this list to Regexp::Trie or Regexp::Assemble.

It might be a roundabout way of doing it, and it might run a bit slow to generate the regex pattern, but it won't require learning anything :O and the regex will be optimized :D