Use this combination to enable cheat mode, first: At the main menu, hold L + R and press Down, X, Up, Y, Down(2), Up(2). Select the cheat option at the main menu and enter one of the following case-sensitive codes.
Level select: KKst0ry
Invincibility: 8wonder
One-hit kills: GrosBras
Full ammunition: KK 999 mun
Infinite spears: lance 1nf
Get Revolver: KKtigun
Get Shotgun: KKsh0tgun
Get Machine Gun: KKcapone
Get Sniper Rifle: KKsn1per
Bonuses completed: KKmuseum