Instructions
Press "Select" to open your PDA, and choose "Support."
Select "Bunker Buster," and press "X" to select it. This will take you out of the menu, and you'll now be holding the laser designator.
Press the "L1" button to crouch, reducing your profile should an enemy target you while you set up the shot.
Aim the laser at your target with the "Right Analog Stick to "paint" it, then press and hold "RI" to call in the airstrike. Keep the trigger held until Misha radios you to say the strike is confirmed.
Move to a safe distance. If your target is close, turn and run as soon as the airstrike has been confirmed. The large blast radius of the bunker buster could cause substantial health damage.