The Lufthansa 747-200F that wiped all its landing gear out during a high speed max weight aborted take off on runway 13 at Kai Tak Hong Kong in the early 80's was trestled in much the same way with beams through the cockpit side windows and upper deck windows. Also, in this case, because of the extensive belly damage the nose door itself was opened and supported on a scaffolding platform. Basically the whole belly was cut off about 12 inches below the floor beams and new prefabricated sections made by Boeing were spliced in. A lot of support was needed to maintain fuselage alignment while all thse pieces were cut out. HAECO had an interesting video of the recovery and repair.