Fear no more htoug, there are several ways to process XML without expat:
XML::Parser::Lite, included in Paul Kulchenko's Soap::Lite, is a pure Perl XML Parser that emulates XML::Parser. It requires Perl 5.6.0 at least.
Matt Sergeant is working on a pure Perl parser: XML::SAX::PurePerl. It is in alpha stage and requires bleadperl (does bleadperl compile on Tru64?).
You can also try XML::LibXML for a parser that's not based on Expat (but on the Gnome XML library libxml2) and that should compile on most platform with gcc.
Of course all XML::Parser based modules won't work then, but SAX based ones will.