I recently brought the book “Japanese Throwing Weapons” by Daniel Fletcher. I may post a review of this book once I have found time to watch the DVD that is included with it. I also came across this rather good video of bo-shuriken throwing. The basic throw he uses is the same technique from the Meifu Shinkage Ryu that is shown in the book.
This method is similar to the push throwing technique I show in my book, but differs in a few details. The technique I show uses a more circular throw and the blade leaves the hand flying point first, the fingertips directed forwards. The Meifu Shinkage Ryu throw is made as a more linear pushing action that swings down to the opposite hip after the blade is released. The fingertips and the spike remain pointing upwards until after release and the missile makes a quarter turn to point towards the target. Both techniques will produce a "spinless" throw, however.
Later in the video the thrower makes both inward and outward horizontal throws and a number of other more advanced techniques. Enjoy the video, he is very well practiced and shows very good accuracy.