So you've never heard of a three engine ferry then? It's just after the chapter about flaps and windshear.
Oh, don't rise to his bait or we'll be bombarded with more irrelevant nonsense, as if wing warping wasn't bad enough. To guys like SSR there's only ONE way to do something and anything else is just wrong. Flap 25
OR flap 30, don't be so ridiculous. Let's ignore what Boeing do recommend and, instead, suggest other techniques e.g. asymmetric thrust which, for some strange reason, seems to be missing from the manufacturers' manuals.
Never mind that Boeing, British Airways and the CAA all approved the steps taken by the LAX 747 crew and never mind that all 3 on the flight deck went through all those approved steps and decided to do what they did, SSL is telling us they were all wrong and he knows. There's only one way to operate an aircraft and that's SSL's way, with one flap setting, wing warping and asymmetric thrust
I'm glad between the likes of Stilton, Masher, Gatbus etc we've established that using a reduced flap setting is (a)a perfectly normal means of operating an aircraft safely (b)is approved and recommended by the manufacturers (who seem to know a bit about the subject and (c)helps to achieve what the OP was asking about in the first place.
I think I'll leave it at that, lest the chaff dispensers return.