During stage 6 look for two tombstones close together as you encounter a ladder. Before continuing the stage and going up the ladder, stand between them and crouch down 7 times to summon Fuzzface. That is all.
By the way, this is helpful for later plays on higher difficulties. Once you summon him during a play through, he stays with you throughout the game and randomly drops health and special gauge items. However, if you turn the game off (even after saving), Fuzzface won't be there when you reenter the game, but you can always summon him again by following the above process.