Auto-enable an extension

Hello,

I am creating a utility which automates the installation of ArcGIS for Desktop 10.1 for all users in our organization. All users are licensed for the TreeWorks extension, so I would like the utility to auto-enable it. I can enable the TreeWorks toolbar using a default Normal.mxt file, but this doesn't actually enable the extension. Is there another way to enable it besides Customize > Extensions and checking it off? Is there another config file or registry entry available?

Thanks,
Wayne