Re: how to affiliate with an organization?
I'd suggest doing the Japanese thing--find somebody who can perform an introduction. Have any of your instructors trained with him? Anybody you've trained with? Anybody you've been on the mat with? Failing that, is there anyone teaching a seminar nearby who is in his organization and who you could meet?
Then find a seminar of his you can go to. You're not going to join his organization without meeting him. Write a letter (in paper) introducing yourself, giving your history, and saying you'll be at such-and-such a seminar and you hope to meet him in person there. If your history includes things that are politically problematic (you trained with another Shihan who was out of favor with Hombu) include it but with language making it clear you wish to leave that influence to come over to him.
The letter can be enclosed by your go-between or sent by you directly if you really can't find anybody.
Be warned, depending on how Hombu is dividing up the world these days, it may not be possible to affiliate with him officially.