First off, you must know the Grip Grab ability. If you don't, play through the game until you do, then return to Jinjo Village. From where you enter Jinjo Village (coming from Spiral Mountain/Inside the Digger Tunnel) turn right to find a desert-like area. Go against the wall and you'll find a ledge which you can grip grab along. Edge your way across the ledge, killing the enemies which pop out at you as you go until you reach the end. Climb up using the A button, and go through the tunnel opening. Inside is a walking B-K game pak with eyeballs. Roll into it and the Ice Key will pop out! Collect it to open the Ice Chest later in the game.