Just a report to help others over a problem I ran into with Microsoft Word (2004 in my case).
After many failed attempts to get MS Word to recognize the Bookends add-in and template (and putting them in the proper folders as described in the Readme file) I solved the problem by quitting all MS Office apps, trashing the entire folder "~/Library/Preferences/Microsoft/" and restarting Word.
Likely the problem resulted from having the Office 2004 trial version on my Mac before installing the full version.
Additional keywords: plug in, plug-in, “Bookends Word X Add-in”