John,
The L1011 TriStar deployed spoilers automatically during the approach; the system being called 'Direct Lift Control' (DLC), which enabled the aircraft to maintain a more or less constant 'alpha' (body angle). Push forward on the stick and the spoilers opened further, dumping the lift and increasing the ROD; conversely, pull back on the stick and the spoilers retracted, enhancing the lift and therefore reducing the ROD. The advantages were twofold, firstly, as mentioned above, it gave a constant 'alpha'. Secondly, the engines were now 'spooled up' in preparation for any subsequent Go-Around.
Big heavy aircaft will glide just like any other aircraft... as the space shuttle adequately demonstrates. But do take a look on 'YouTube' at a Shuttle approach and you'll see just how steep that glide angle is. I obviously haven't chosen a great example by discussing the shuttle techniques because the shuttle does indeed have to 'pitch-up' massively during the last couple of miles to reduce speed and arrest the 'frightening' rate of descent.
A B777, or any other big aircraft for that matter with no engine power (or limited throttle response), would have to plan a similar technique... but from 600 feet and two miles it's too late to achieve that sort of profile, because all of the energy has been lost within the normal 3-degree planned approach path... it's not a recoverable situation.
As for bringing the flaps in a notch or two... absolutely NOT; it would simply have brought the aircraft much nearer to the stall and would have actually dumped the aircraft onto the ground much shorter than where it ended up... probably in someones living room in Hatton Cross!
The boys did good.