Pretty unusual to have a knock sensor failure -- What are the symptoms?
Either way, as mentioned above, it is not a difficult job. Just pull the intake, you'll find the knock sensors immediately below. You'll need to remove all the wiring, the steam / coolant hoses that run to the throttle body, fuel line(s).
More than likely be able to re-use the stock gaskets, though new are never a bad idea on a higher mileage engine where they may be a bit cooked.