I first encountered the idea while working with the Voyager Tarot of James Wanless (I had already been using the "numerological counterpart" technique). In an email conversation Dr. Wanless told me that the Voyager is Thoth-based but I don't believe Crowley ever got into this sort of thing. It looks like the Voyager companion book was published in the late '80s and Jodo's book was first published in 2004, so I'm wondering where it originally came from.