SS Take Over
If LHS PNF was convinced that he needed control all he needed to do was push SS forward while at the same time pressing and holding the take over button on the SS and saying, "I have control". If RHS PF does not respond in time honoured aviation fashion, "You have control", PNF keeps the TO button pressed.
If I remember correctly all the time the to button is pressed you have control and after 30secs holding it pressed the opposite SS is latched out.
Correct CRM, I have/You have, allows takeover without the need to lose the other SS as the taking over pilot can release the TO button before 30secs has elapsed.
Press and hold, until release is acknowledged, is taught for capts taking over in the event of a botched landing from the other seat!