Start the game on ONI:sword base, after the part were you blow up the wraith and get the warthog (you will need two people).

So get one player to head to the right. After you've destroyed the ghost go around the turn.

When you see the trees to the right head there and jump up on the rocks there and go all around the edge till the words "hold B to open door" comes up and then stay there.

Now player two take the warthog and head to the left and blow up the ghost.

So now you have to head up by the revenant you can either kill all the enemies there or skip them all. So any way head up behind the building closest to you.

Head to the far edge building and look to the North-West and run up to the rock.

Head near the top of the rock and walk around it till the words "Hold B to open door" comes up again.

Then both players hold B at the same time a thing will come up saying "reach racer" and you and the other player will be put in a race against each other.

[unconfirmed]