The XML::Twig documentation says this:

XML::Twig implements a subset of XPath through the get_xpath method.

If you want to use the whole XPath power, then you can use XML::Twig::XPath instead. In this case XML::Twig uses XML::XPath to execute XPath queries. You will of course need XML::XPath installed to be able to use XML::Twig::XPath.

so do that.

Makeshifts last the longest.