Okay it might not be what you think it would be like. But it does fire explosive that could be regarded as rockets.
First this mod changes the minigun on the Annhilator to a rocket launcher.
Second the rockets may occasionally explode by the side of the helicopter and so it is a good idea to download a Tank Mode/ Vehicle Invincibility mod/trainer as even if they don't explode by the side of the helicopter the rockets will blow up alot of cars and they willl probably damage your helicopter.
Also the rockets fire at a downwards anlge so you have to aim higher than normal to hit your target.
REMEMBER THIS IS A BETA SO ANY SUGGESTIONS ARE WELCOME.
Also extract the files with WinRAR or a similar program.
Thanks for your comment. I have already corrected that error though over on the GTAForums where I posted this mod http://www.gtaforums.com/index.php?showtopic=401538&st=0&#entry1059037619 . But well done for placing it in the right place, I was afraid I would get a load of angry people bombarding me with hate over the incorrect ReadMe.