To augment my study of the Mehegan books, I have found a very good podcast by a professional keyboardist in London, Paul Abrahams. His methodology general follows Mehegan, and his presentation is well-paced. He may be contacted through his website. I am through podcast #4, which is all review for me at my level of musicianship, but I am sure the lessons will become more complex.
The benefit here is that I can listen to this podcast at times when I don't have access to a piano. Keeps the thinking going.
There are many music instruction podcasts available, and I intend to sample them from time to time. So far I am very pleased with Paul's.