You can jump right to the timed final challenges in the game's Match Race mode. To do so, enter the following codes at the options screen:

Novice Final Challenge
Track Name: Sub-Zero Assault: Spinal Damage
Code: JAS3IKRR

Hard Final Challenge
Track Name: Sub-Zero Assault: Ballistic
Code: 2AUNIKFS

Expert Final Challenge
Track Name: Avalanche Alley: No Way Out
Code: EATFIKRM