This was almost certainly drawn out by hand, waypoints (lat/lon) and turns were plotted and then inputed into the flight management computer, and there is a good chance the plane just flew itself as told.

Although given it was flown at such a lower altitude below 15k feed near Moses Lake (which is where Boeing does a ton of testing at that airport) it's possible the pilots hand flew this by following a pre-plotted magenta line already plotted on a map for them.