All very fine if you have a compliant captain who is more than willing to hand over control meekly when his 240 hour support pilot grabs the controls.
But if the captain asserts his command authority backed by the Regulations, and tells the lad to bugger off and handle the radios, then the mantra of Question, Challenge, Take Over is yet another motherhood statement written by the gurus of the CRM tribe. I have yet to see any official guidance from a Regulator or any other authority on the specific method a first officer is supposed to fall back on to physically take command of the aircraft.
Crash axe or fire extinguisher, which ever comes to hand first.