Instructions
Grasp the PS3 controller in both hands in such a way that you can get quick access to both buttons that you want to tap. If you need to tap two of the triggers, place your index fingers on the trigger buttons. If you need to tap two face buttons, place your index finger on one of them and your middle finger on the other.
Tap the first button, then tap the second button with your other finger.
Tap the first button again, then the second button. Keep alternating between the two buttons slowly building up rhythm and speed until you reach the desired pace.