Instructions
Select the "Hack" command when standing next to a computer you want to hack by pressing the "A" button when prompted. This will activate the computer hacking screen, and reveal several nine-digit number sequences on the left of the screen and four sets of numbers on the right side of the screen. One of the set of numbers on the left side of the screen is the correct code, but you'll need to determine which number that is by watching the numbers on the right side of the screen.
Watch the numbers on the right side of the screen, and look for any of the numbers to become highlighted. When a number becomes highlighted, use the left control stick to move the cursor to that number and press the "X" button. This will lock in that number on the left side of the screen as part of the correct code.
Repeat the process of waiting for the numbers on the right side of the screen to highlight, moving the cursor to those numbers and pressing the "X" button until one of the sets of numbers on the left side has been fully highlighted. Select the fully highlighted number set on the left side of the screen by using your left control stick and pressing the "X" button. Selecting the correct number set on the left side of the screen will unlock the computer, completing your hack.