Hold Down until you stop moving. Then, hold A to pick up your board and start walking.
Successfully complete the Pro Challenges to unlock Mindy, Frycook, Momo and Roger.
Spend $240 at the skate shop.
Get all goals in a level. Note: This must be done before any of the buyable cheats can be used for that skater.
Spend $40 at the skate shop.
To skitch a car, go behind a car and hold A + B.
Get all 90 packages to unlock The Zone.
Win the Pro Objective for that skater.
Go to the skate shop and select "Change Deck". The board under "Custom" is the Tony Hawk's Pro Skater 4 board for Neversoft skaters.
Spend $40 at the skate shop. Press B to fly up, A to move right, L to move left, and R to hover.
Get all the gaps on each level except The Zone to unlock the "Turbo" option.