I made a plugin that does this. It works in Sublime Text 3, though I have not tested it in ST2.

https://github.com/rosshadden/sublime-xpath

The one caveat is that it has to be formatted XML. IE each child node has to be indented more than its parents.

-1.  I know my opinion is just one of thousands, but I feel like this goes against everything I like about Sublime -_-.