Instructions
Turn off your PlayStation 2 using the "Power" switch on the rear of the console. Shutting it off using only the "Power" button on the front of the console is not enough. The rear switch must be flipped to "Off."
Plug your PlayStation 2 controller's USB cable into the PS2 console's USB input.
Flip the "Power" switch on the rear of the console to "On." Press the "Power" button on the front of the console to turn on your PS2. Insert the game disc you want to play. You will be able to use the USB PlayStation 2 controller just like a regular controller.