Hold Pause + Option and keep them pressed during the entire code. Press 1+ 3. Then, press 2 + 5 + 7 + 9. The Predator will laugh to confirm correct code entry. The following codes may now be activated.

Security clearance
Press Option + 6 to raise or Option + 9 to lower.

Toggle motion tracker
Press Option + 8.

Recharge all weapons
Press Option + 1 + 2 + 3 + 4.

Toggle shotgun
Press Option + 1.

Toggle pulse rifle
Press Option + 2.

Toggle flame thrower
Press Option + 3.

Toggle smart gun
Press Option + 4.