Pause gameplay, hold Numpad-7 and press Right, Up, C, V.
Cheat Mode
Pause the game, then hold Numpad 7 and press Spacebar, Spacebar, Spacebar, C, V, Up, Down, Left, Up, C, V, Spacebar, V, B, Spacebar, V, B. The pause screen will shake if you entered the code correctly. Next, select the "End Run" option from the pause menu. All cheats, FMV seqences, and skaters will be unlocked.
Fat Skater
Pause gameplay, hold Numpad-7 and press Spacebar, Spacebar, Spacebar, Spacebar, Left, Spacebar, Spacebar, Spacebar, Spacebar, Left, Spacebar, Spacebar, Spacebar, Spacebar, Left. Keep repeating to make skater fatter.
High combo
To get a high combo, get a bit of speed, then ollie, do a fliptrick and get back into manual. repeat this a couple of times, than manual up a quarter pipe or slope and do a grab trick e.g benihana.
Neversoft Skaters
At the Main Menu, hold Numpad-7 and press Up, C, C, V, Right, Up, B, V. Now create a skater with a Neversoft Dev Team name.
Raise Stats to 10
Pause gameplay, hold Numpad-7 and press Spacebar, V, B, C, V, Up, Down.
Special Meter Always Full
Pause gameplay, hold Numpad-7 and press Spacebar, V, B, B, Up, Left, V, C.
Thin Skater
Pause gameplay, hold Numpad-7 and press Spacebar, Spacebar, Spacebar, Spacebar, C, Spacebar, Spacebar, Spacebar, Spacebar, C, Spacebar, Spacebar, Spacebar, Spacebar, C. Keep repeating to make skater thinner.
Turbo Mode
Pause gameplay, hold Numpad-7 and press Down, C, V, Right, Up, B, Down, C, V, Right, Up, B.