Lol, this happened to me yesterday on the final leg of a 1000 nm, 6 airports spread out subsonic touch and go run. I started out with 52 tonnes of fuel, thinking that should be plenty for that distance, and put 10 tonnes of that spread between tanks 9 and 11 for CofG management.
I was on descent to the final airport when suddenly all 4 engines spooled down. I frantically switched to the flight engineers panel to find tanks 1 thru 4 all empty but 9 and 10 still had that 10 tonnes between them. No time to RTFM so I just turned on the all pumps on 9 and 10 and opened the standby inlet valves for 1 thru 4 and fuel started flowing into them.
Luckily, Concorde is a slippery snake on descent, so I was able to get a couple of engines restarted before I got close to stalling. One final challenge was that I had left AT on, so when the first engine had restarted, engine 1, it went to full throttle with reheat, giving me a sudden, massive yaw to the right which I corrected by kicking off AT.
I landed without further incident but still gave my flight engineer (me!) a good rake over the coals for letting fuel get so low that we lost all four engines at once when it could have been avoided entirely. Nonetheless, it was fun trying, and ultimately successfully, dealing with this self-imposed inflight emergency on this magnificent aircraft! 
