With Apache2.0 and mod_perl 2.0 (both in beta), you could build handler-queues (first is e.g. mod_perl and the second another filter). But I don't know a direct way. Just maybe if you write Code with Apache::Registry, you could perhaps build a string containing the whole HTML-code, filter it or do whatever you want and then return it to browser. But I'm not sure if this is in the sense of mod_perl :-)

Please, beware that I don't know much about Webprogramming, since I hardly ever cope with cgi, mod_perl or the like...

Best regards,
perl -le "s==*F=e=>y~\*martinF~stronat~=>s~[^\w]~~g=>chop,print"