Is anyone aware of a current implementation (or effort towards one) of the XPointer W3C specification? (3 parts: [1][2][3])

I am in real need of using an XPointer library, and I don't seem to find any CPAN module that is dedicated to it. The only one is XML::Grove::XPointer, but that seems deprecated... Any hints are appreciated!

Background use-case:
I am doing some natural language processing on XHTML+MathML documents. Since I am mostly interested in processing the math, in the context of the surrounding natural language, I need to stick to XML. The moment I want to start annotating, I need XPointer annotations for the text, as XPath is not fine-grained enough.