Instructions
Plug the Gameshark into your Nintendo 64's cartridge slot. Push the game cartridge into the slot located at the top of the Gameshark cartridge. Turn on the console.
Choose "Select Cheat Codes" from the main menu. Locate your game in the list of games and press "A" to view the cheats available for it. Highlight a cheat code you would like to activate and press "A." Repeat for any other codes you want to activate. Press "B" to return to the "Select Cheat Codes" sub-menu.
Highlight "Add Game" (located at the top of the "Select Cheat Codes" sub-menu) if your game does not have cheats preloaded on the Gameshark cartridge. Press "A." Follow the prompts onscreen to enter the name of your game. Choose "New Code" at the top of the code selection screen for the game you just added to the database.
Visit the GameGenie website to locate the game you would like to add cheats for. Find the cheats you would like to add and copy the hexadecimal string exactly as it appears into the entry field. Double check to ensure accuracy, press "B" and confirm the code by pressing "A." Follow the prompts to name your cheat code (for example, "Infinite Gold"). Repeat this for each cheat code you want to add for the new game.
Press "B" twice to return to the main menu. Highlight "Start Game" and press "A." Choose "Start Game with Selected Codes" to begin the game with the cheat codes you have chosen.