The other two wrote their own books.
Peter Kreeft wrote a book about the three of them, Kennedy, Lewis and Huxley, meeting after their deaths and the discussion they might have had.
Between Heaven and Hell: A Dialog Somewhere Beyond Death with John F. Kennedy, C. S. Lewis & Aldous Huxley
http://www.amazon.com/Between-Heaven-Hell-Somewhere-Kennedy/dp/0877843899
It was sad that C.S. Lewis death received no headlines because of the death of Kennedy.
However, the more I have thought about it, I’m sure Lewis would just fine with that.