It's not a cheat but a great place to snipe people.

On one side of the map is a elevator and on it is a ladder. Climb a ladder at you should see a platform, jump on.

Then when you get to the crane (click A, A) you should be able to go onto the crane, then go left to another platform. Go on it.

Then the should be a window in front of you shoot it then jump in. It's a great place to snipe. I recommend a thermal.