I'm not sure why you had RPM problems, but the first place to look for an RPM of expat is on the Mandrake CD. I'm not a mandrake user, but expat is a standard feature of RedHat.

If you don't want to use XML::Parser then XML::Simple version 1.08_01 or later can work with *any* SAX parser. Just install XML::SAX and then say XML::LibXML.