I need to simulate stress of a threaded-in part which has hexagon wrench flats. I'm placing a fixed load on what would be the threads, and applying a torque to each of the hexagon sides and selecting "total" for the torque value so it's distributed. Would this be the correct way? Thanks in advance.

I think its right way to apply torque.

So select all the faces of hexagon sides and apply a total torque.