Instructions
Delete the 1.3 patch. You can do this by going into the PS3's saved game data files, then click the "Call of Duty 4" folder.
Open the game.
Skip the update by pressing the circle button.
Trick the PS3 into thinking the 1.3 patch is installed by lagging it. This is the hard part. Try logging into XMB while the game is loading. While logging in, repeatedly hit the circle button to stop the update. This might take a few tries.
Play the game. You can play in cage-match or free-for-all mode. The game will only allow you to play with other people who don't have the 1.3 patch. You will be able to call up a helicopter as many times as you like.