XSITE_HOME to point to the chosen directory.XSITE_HOME/bin to your system path.
On UNIX systems, ensure that you have the correct permissions to execute XSITE_HOME/bin/xsite
(defaults to chmod ug+rwx o+r).
On Windows systems, replace / with \.
The required inputs for XSite are
xsite -m [path-to-sitemap] -s [path-to-skin] -o [output-directory]
XSite can be used as a plugin as described in plugins.