To do this cheat first do the unlimited lives cheat first. Then when you're at speed 5 go to the other side of the halfpipe. Finaly press B+left or B+right.
Select adventure mode. Press Start, A, Select, B on controller two during game play. Then, press Right for the Mall, Left for the Beach, or Up for the Planet level.
To get unlimited codes on the halfpipe you have to push select to go to the halfpipe. Then you have to move him to the top and all the way back of the top of the ramp and when he scratches his head hold up and press star and select till you hear a noise.