Press B(2), A + B, A + B + C, A + C immediately upon entering the menu screen. Note: Entering other action on the controller before the cheat sequence, including using the D-pad, will disable the cheat. A sound will confirm correct code entry.
Begin game play and proceed to the ambush scene where the man riddled with arrows says "Stranger, this is the map to the gold. The Padre has the other half. Watch out for... Mad... Dog" You have approximately one second to shoot the map when it appears during this scene. This unlocks half of the cheat functions.
Proceed to the scene where the priest says "You look honest my friend. Find the treasure, return it to the mission and receive your reward... in heaven". The second half of the map will rotate as the priest speaks. Quickly shoot the map when as it turns into a more square position to enable the other half of the cheat functions. The cheat functions include unlimited ammunition, unlimited lives, pressing C to automatically shoot the target, and Gatlin gun mode.