Since XML::Simple got a bugfix release, and XML::Handler::Trees got released incorporating my patches, I've released XML::SAX::Simple to CPAN.
So now you can use any PerlSAX2 parser in association with XML::Simple:
use XML::SAX::Simple qw(XMLin);
my $config = XMLin("config.xml");
There's some stuff I'd like to support, for example currently there's no way to use XML::Simple as a SAX Handler, which would be nice, in that you could create