I read that and was actually trying it until I told my local pro about the technique ... he told me that cupping wasnt something that he recommended especially for a newbie just learning to hook.
Ron always tells me if someone wants to learn to hook the ball, you might as well learn to do it right, why bother learning the wrong way and have to take years to unlearn and relearn like I have.
Either way I've found out that the release timing is the most important thing ... staying behind the ball until it reaches the slide heal then release the thumb and turnin to about 45d with the fingers lifting up through / around the ball. Getting the thumb out consistently is the biggest obstacle at least it was/is for me.
The problem you are going to have is the fact that your thumb is not supposed to hang onto the ball, the ball is supposed to hang onto your thumb and the centrifugal force of the ball swinging from your shoulder is supposed to pull the ball from your thumb without effort at just the right moment without you having to release the thumb, this way it is repeatable as long as you don't interfere with it, like knuckling your thumb to hang onto the ball.
This is why I have been saying over and over how important it is to have the proper span, thumb size, thumb pitch, and finger pitches to be able to release the ball properly. If you are truly gifted and are able to release your thumb at exactly the right point every time, and there are such people, then put me on your ignore list, but the rest of us mortals you will need to spend some time and money with your local
Pro Shop to get your grip exactly right.