HT Games
The Easy Way
Start the game normally. You actually have to be in the game for the cheat to work. Then press ̶0;R1, R2, L1, R2, Left, Down, Right, Up, Left, Down, Down, Left.̶1; This will unlock a series of weapons, including a machine gun, katana, grenades, uzi and shotgun. It will also give you the rocket launcher.
Use your L2 or R2 button to sort through your weapons until you arrive at the rocket launcher. The rocket launcher will appear in Tommy̵7;s hands. You needn̵7;t press any other buttons. Repeat the code as soon as you run out of ammunition. Also be careful not to stand too close to your target when you fire the rocket as that will have a rather negative effect on your health.
The Old Fashioned Way
Save up your money. You can purchase the rocket launcher at Phil's Place for $8,000 but only after you complete his missions. If you don't have $8,000 on hand, try smashing some parking meters for some quick cash. After you've smashed them, return and smash them again. They automatically will refill with cash. You also can try to earn extra money by doing taxi missions. A rocket launcher is also hidden at the Hooker Inn's pool.
The Hard Way
You can have the rocket launcher automatically stored at your Starfish Island Mansion and Ocean View Hotel hideouts by finding 70 hidden packages. These packages are hidden throughout Vice City, and you will have to pay close attention to find them. Many are on top of buildings or stashed in bushes. Explore every corner of the city, and you eventually will find them. It will be worth your while because it will unlock an assortment of weapons at your hideout. All you need to do is return, pick up the rocket launcher and continue the mayhem.