Alan's seminar was on a different than normal way to write essays. First he went over the basics, ie don't write a biography, everything must be relevant and to the point. Structure is also very important for an essay.
The main idea is to start with the conclusion. This means you know exactly where you are headed in the essay and can structure each paragraph to get there. This differs from the traditional approach because you don't start with the introduction. Afterall it is easier to change bits in the conclusion than it is to change bits in the introduction.
The imap fits into this by collecting all the information you need for the essay onto 1 or 2 pieces of paper. Now this is done when you write the essay you can easily find any quotes and arguments that are needed.