How do I use the Groups.pm in Request Tracker?

In lib\RT\CustomFieldValues\ there is the groups.pm file which is supposed to be an example of how to get data into a custom field, but how do I actually use that once I have written it? Does anyone have any documentation or a sample of this?

From stackoverflow

• I have finally figured it out, to use the Groups.pm module you need to go to /opt/rt3/etc and edit the RT_SiteConfig.pm and add the line

  Set(@CustomFieldValuesSources, "RT::CustomFieldValues::Groups");
  

  Restart Apache and it will be available as a new field source.

  I have written a blog post on doing this which also includes details on how to build your own module in case anyone is interested in doing this: AD Lookup Control in Request Tracker