The solution was to use the Formativ Stationery solution. Since the original question was asked, the stationery solution has gone through several versions. I would suggest you download the Stationery solution and see if it meets your needs.
In terms of having the stationery appear when a new message is composed, the answer was to integrate the stationery solution with the OnCompose event associated with an email message. The solution, out of the box, isn’t integrated with this event, but it is easy to do with Formativ Creator.