Cheat Mode:
Press Start to pause the game, then press Select 16 times. You should now see a cursor on the status line. Hold A + B and press Left or Right to move the cursor. Press Up or Down to change the number of current coins, lives, hearts, or time.

GameShark Codes

Have All Keys   010f5bca
   
Rapid Jump      010093c0
   
All Music Coin  01085cca
   
Max Coins       010904ca
                019905ca