Hi there Jason,
I faced a similar problem when I was attempting to create a catalogue of images and shapes to be used in PowerPoint brand presentations, to allow my fellow workers to access a set selection of imagery that would represent the business consistently. However, I was unable to solve the issue and resorted to a PowerPoint presentation design service company called article10.com. They are able to create templates and a toolbar that enables you to have a set theme to use in all your presentations. Hope this helps!
Sian.