Instructions
Load a game and approach a normal enemy guard, found in most areas. Do not attempt this on a significant enemy such as a large, armored guard with a minigun.
Press the "Left" button on the D-pad to equip a regular pistol, such as the 92FS (not a high-powered one, like the Desert-5).
Run toward the guard and hold the "L1" button down to aim. Point at his torso and then press the "R1" button to shoot him once. Release the "L1" button.
Stand immediately next to the enemy and press the "Square" button.