Select the 'Cheats' option at the 'Main' menu and press Down, Left, Up, Right, Down, Left, Up, Right, Down. When this code has been enabled you will not be able to 'Save' the game but you will have unlimited ammo to create mayhem in it.

If you're struggling to find ALL 6 trophies then the following list will point you in the right direction.

Michigan J. Frog Trophy:
In the 'Assembly Line Insanity' level where the black knights are there is a breakable wall on your way to the platform where you trigger the switch.

Porky Pig Trophy:
Before you get to the big black knight at the end of the 'Muddy Evil Forest' level look for a tree top by one of the houses and the trophy is in that area.

Road Runner Trophy:
Go to the swinging pendulum stage in the 'Pyramuddle' level and at the opposite side of where you entered there are some boxes. Smash open the boxes to find the trophy.

Tweetybird Trophy:
Look for the door which is near the end of the 'Whack Tastic Robo Bash' level which has 'Monster' written on it. The trophy will be in the area above the door.

Wile E. Coyote Trophy:
Go up the hill at the beginning of the 'Volcano Way Out' level and at the first tree on the left fall down the ledge and trophy will be on the left.

Yosemite Sam Trophy:
In the 'Low Noon' level where you face the first big cowboy go back past the tracks and then to the right and the trophy is on top of a house.