My understanding is that one hand starts at the base and you apply pressure one finger at a time working from the finger closest to the base. After all your fingers are applying pressure, and you are HOLDING the pressure, you do the same thing with the other hand above the first one and again apply the pressure the rest of the way up to the head. You don't have to slide any skin and the pressure you can achieve is tremendous. With the second hand holding pressure, you repeat the process starting with the first hand.
A word of caution!!! Be careful not to cause too much pressure in the head! You can burst a vessel!