He writes about it here too.
Maintain the Squat - Train the Deadlift
Most of his focus is on the single leg version.
I'm interested that his basic motion is really a still legged / Romanian deadlift - the hips are doing the work, not the knees. It is also the same hip hinge movement that Esther Gokhale teaches as a basic safe way of bending over - thrust the hips back. It is also the key to the swing