"I believe the controls to feather was between the pilot seats and slightly rearwards, and in the dark the wrong knob was selected."
I think you are referring to the idle cut-out knobs which were behind the left-hand pilot's seat. They were impossible to see without a large amount of contortion and were normally selected and pulled by feel.
The feathering/unfeathering buttons were centrally mounted on the glare-shield, in front of both pilots. The button was pushed in to feather and pulled out to unfeather. (I think that the engine fire warning lights and extiguisher buttons were also close by.)
The report provided by the link doesn't mention either of these controls but instead refers to the fact that the pilot was flying from the LHS when he was more used to the RHS. Also, the engine instruments were on the RH instrument panel and might have been misinterpreted. Although he told ATC about the correct engine that was showing problems, he ended up shutting down the other one. Eventually the failing engine gave up as well.