I only discovered g-cpan *after* writing this, of course. However, I need to patch Makefile.PL, so the ebuild is probably still useful. HTML::WikiConverter converts HTML to various wiki dialects, including MediaWiki for Wikipedia
Created attachment 61474 [details] HTML-WikiConverter-0.23.ebuild
Created attachment 61475 [details, diff] Patch Makefile.PL to notice html2wiki
Mass re-assign.