I wouldn't be surprised if you can. On the flight manifest, they listed that one of the passengers was a flight engineer. Whether he had his "laptop/smartphone" in his possession at the time does bring up a red flag.
I don't know 777's. But I do know MD-11's, and on the MD-11 you would have to be in the cockpit at the flight computer to do that. But it's easy to override the flight computer in-flight, and enter alternate courses, etc. from the cockpit.