Instructions
Insert the "Mario Kart DS" game cart into your Action Replay DS device.
Insert the Action Replay device into the game port on your DS console. Turn the DS on.
Select the "Code Select" option in the DS main menu to access the code select screen.
Select the "Add New Code" option in the code select screen.
Enter the name for your code using the on-screen keyboard, then select the "Next" option to continue.
Enter the code you have created in the Code Entry screen, using the on-screen keyboard. The best way to create new codes is to study existing "Mario Kart DS" codes, then edit them slightly to see what in-game effect they have. Select the "Next" option to save the new code to your code list and return you to the Code Select screen.
Select your code in the Code Select screen, then press the "Start" button on your DS to begin playing.