I've done a bit of research and, as far as I can see, this grip is unique to "The Count", who used to post as Drey on 21ace and a couple of other forums. As far as I can see, it bears some resemblence to the look of a modified Erdnase grip, and the pressures of the grip described in Maskelyne's Sharps and Flats. If you want to look at it in depth then it's detailed in "The Count's Inquisition of Shuffling and Dealing Volume 3" ebook.