TIA,
The document "Implementing David Allen's Workflow Processing Using Microsoft Outlook" is not a how-to for implementing the features of the GTD add-in. The Implementing document is a tutorial of Outlook's functions and abilities and how they can be used with the GTD processes. The add-in is a set of modifications to Outlook that adds macros, buttons, and other functions to Outlook. For example, the "delegate" function and button in the add-in allows you to forward a message to someone, create a new waiting-for task, set a reminder to follow up on the waiting for, associate the task with a project, and archive the message in a saved folder. Don't expect the "Implementing" document to give you the info that lets you write the macros to do all of that.
Having said that, I don't use the add-in; I use the tips in the "Implementing" document and think they are worthwhile. I haven't needed the additional functions. Others who post on this board use the add-in and love it. Just remember that the add-in and "Implementing" are different products with different goals in mind. It just depends on what you want to accomplish.