for taxying, they had a system of shutting down the two outers, and just using the inners on a restricted power setting (a blocking device on the throttles if I remember)
When we arrived at Wick, the captain pointed out to the F/O (a new boy) that with the slope of the runway, it wasn't a good idea to use this taxy mode too early, as with the restricted power settings on the two remaining engines, there might not be enough thrust to get you up the hill, and embarassingly, you might have to re-start the two outers!