Dont make too complicated.
I know of some customer support centers which avoid any tickests for over complex emergencies, because it is a pain to get access to solve the problem.
Rather choose the correct setup and persons in the first place, log activity and have a central admin responsible for who has such access to request more power.
You will either have emergencies from 9 to 5 or they will share the passwors like in the old days again if it is too complicated. Defeats the purpose....
Cheers,
Julius