From the main menu, head to Racebox mode and create an event with the following settings:
GAME MODE: Wipeout HD
RACE TYPE: Tournament
SPEED CLASS: Up to you (whichever speed you're comfortable with)
WEAPONS: Off (to avoid being blindsided by a powerup)
AI DIFFICULTY: Skilled
Hit X to confirm these settings, then you'll be in a track selection menu. Scroll to the track Anulpha Pass and hit the square button 8 times - this will add the track eight times to the tourney. It's a quick track and very easy to drive on, plus you can steer to an upper ledge which has three turbos to speed you up and a gap to barrel roll on (though bear in mind, there are no weapons to replenish health). You must win ALL 8 races in first place, otherwise you'll be forced to restart again.