Going off the picture I teach a little different positioning as the first method of doing it.
Take the legs and figure four them from there, right foot into left knee. Then use the left foot to either push out on there other leg, or just hook under it.
This will prevent them from rolling with it as there other leg is tied up, and rolling the other way does damage to them.
It is also a very secure position, so if you can achieve it you can hold it for a while, so it you want you can roll, get the position, and not crank on it without them being able to do much, call that the win.
Heel hooks are pretty versatile and position can vary, I just like the one I described as it is very secure