SSR,
Not hard at all - the use of throttles instead of flight controls was used by Bryce McCormick to control his DC-10 after the rear freight bay door blew out in the "Windsor Incident" - reference Chapter 8 of "Destination Disaster". Apparently this procedure was well-known to the McD instructors but only demonstrated when requested.
To bring the discussion back to current practice, there are multiple systems that now have a direct bearing on changing the aircraft's pitch, roll or yaw. Exactly which ones should be considered will depend on the detail design of a particular type - if we were still maintaining a Concorde we'd have to include the fuel transfer system!