API usage and examples?

Problem/Motivation

There is documentation on d.o that mentions an API and links to http://api.lullabot.com/about (which does not work).

https://www.drupal.org/node/264655

There is also a file in the module named xmlsitemap.api.php, but this file is filled with functions that don't seem to actually do their prescribed functionality. They run database commands on the "mytable" database table, which doesn't exist, and there is no additional documentation or use of these functions (that I can tell).

Is there an API for XMLSitemap? What I am interested in doing is adding routed pages from a custom module into the sitemap, which are not nodes in Drupal and aren't exposed any other way.

I am considering just extending my custom module to create a custom Menu, and add that to the sitemap using the Custom Menu Links functionality, but I am curious if there is actually a usable API for this module, and if there is, if there is any relevant and up-to-date documentation on how to use it.