I have added a link to the Itten Dojo's "Sword and Spirit" Newsletter of November, 2005.
Over the years, I have discussed my ideas on how to refine aikido training to facilitate the development of effective atemijutsu and kaeshiwaza, as well as effectively laying the groundwork for a more natural development of freestyle training and for the inclusion of internal training skills. Not infrequently, I get inquiries to go into more detail on this training method. As the Itten Dojo is currently the only dojo I know of which uses this methodology, this article best represents its current status. You will notice that it is primarily about solo exercises - but I want to be clear that they are NOT "internal training exercises" as presented. That said, with the proper training of such a methodology, the movements could easily become the "shell" in which to place one's internal training practice. If one actually wants to train in the method, you should contact the Itten Dojo at http://www.ittendojo.org
The file is a downloadable PDF at http://www.edgework.info/articles.html