Al Haynes could have used this system in the DC10 except that that airplane does not have the electric backup to the flap. One point of the Boeing system is that an airplane will fly the speed at which the failure occurred, unless you can change the trim setting somehow. The DC10 did not have that option, but the 747 Classic does. As the flap is extended, the trim speed reduces. As the gear etc is moved, the trim speed can be changed to adapt by extending the inboard or outboard flaps accordingly. With engine power to assist in turns, rate of descent and speed adjustments, it is possible to set up a slow approach with flap set and by moving one set of flaps to even maintain a glidepath. It is an exercise you can try in the sim. Turbulence would be a bad thing, but still better than just sitting there on your hands.
One note of warning; do not pulll the throttles closed for the touchdown, or else the airplane will nose in. Wait until you are on the ground.
In the 744 you can achieve the same effect by pulling either the inboard or outboard flap circuit breaker (just behind the FO seat) and extend or retract one set to achieve the same thing, but with a hydraulic fuse, that should not be necessary.
I remember wondering out loud why those arrows showing the trim change were on the electric switches for the alternate flap in the Classic and was lucky enough to be flying with a smart South African fellow who explained it all to me. He said they used to include it in the type rating courses but dropped it when told the chance of such a failure was so low. A few hundred people might, if they were able, correct that opinion.