Just ran across this video, I'm going to have to try it.
The other technique I've seen is to make two L-shaped jigs, Put one on each side of a board to be dadoed. Put your piece to fit in the dado between them and slide them together and clamp in place. Then with a router with a top bearing, zero clearance bit less than but at least half the size of the dado, run across one side and back the other.