Using the PS bolt comes from gasoline-engine procedures in which case, the spark plugs are taken out, eliminating all compression. It's a good method and it allows 1 person to turn the engine and see the cam position.

On a Diesel, with all its compression, I can't imagine doing it this way unless the glow plugs or injectors are removed. Otherwise, I agree with the other guys - use the crank-pully bolt.