Things You'll Need
Instructions
Navigate to the Wii Brew website (see Resources) and click on "Download" to save Gecko OS to your computer. Extract the Gecko OS application to your computer and transfer to a folder named "Apps" on your SD card. Navigate to the Ocarina Code Manager download link (see Resources) and click "Save" to save the Ocarina Code Manager to your computer. Install the Ocarina Code Manager by double-clicking the setup file and clicking "Next" when prompted. Choose a directory to install the program to.
Navigate to the Wiird code database and click on "Wii." Click on the letter "M" and find the appropriate version of Mario Kart Wii for your console. Click on the Mario Kart game for your console and click "Export to TXT."
Open the code file in Ocarina Code Manager and toggle on and off the cheats you would like. Cheats available include growing shells, infinite bullet time, infinite super mushroom, big shells, and many more. Click "Export to GCT" to export the code file to your computer when finished. Transfer the Wiird code file of Mario Kart Wii to a folder named "codes" on your SD card and insert into your Wii. Gecko OS will read the codes out of this folder when you launch Mario Kart Wii from Gecko OS.
Launch the Homebrew Channel and select Gecko OS. Select Mario Kart Wii to run and the hacked cheats will be loaded along with your game. You will now have the cheats in game play.