ok so i assume u deleted the saved data for call of duty 4, then u copied the codes from your flash drive.......after u do that, you need to go to game data utility...if u dont delete the game data utility, the codes will not work and you will not get the black update screen
as for the question about having a friend, no u do not need a friend to do it with because your friend list does not work when u properly bypass. So, all u need to do is bypass and find a game with other hackers