The xPLGirder component is a Girder component (written in Lua) that connects Girder to the xPL network. The component was initially written by HarleyDude (Richard A Fox Jr.). The download has a readme file with detailed instructions on installation, configuration, etc.
It can be downloaded here (downloaded 1010 times).
Support is provided through this thread on the Promixis forums
The sources are maintained in the xPL SVN repository. Filed under tieske.xPL_Girder_plugin.