take the one for the start switches, fuel pumps or the electrics panel with you. It won't take you one minute to take them out, since the connectors on the back are usually cannon plug types and I doubt you'll get the engines started or the plane moving without boost pumps,..
You've never heard of gravity/suction feed? I'm sure I wouldn't be the first or the last person to successfully start up an engine after forgetting to turn on the boost pumps. Also, the last time I had to remove an overhead panel, the wiring was so tight I had to pull out several panels... and use cannon plug pliers...but maybe an MD11 is different from other aircraft?
By the way, something which looks like a screwdriver will probably be confiscated before you get on the aircraft
I think pilots should be looking for quick, practical ways of disabling an aircraft. Snapping off ignition CB's.. pah... Most aircraft have 3 sets of breakers? (Sys 1/2 and Standby). CB's will break when you don't want them to... Good luck
intentionally snapping them off.
Physically lock the cockpit door and jump out the window (hatch). This will give you enough time to disable the aircraft from the outside (as someone has already suggested).