Extracts direct from the Boeing Flight Crew Training Manual - in this case dated December 2007. (My bold emphasis).
Intruder - Having been on the -400 since 7/90 and the Classic from 1984, now some 14,000 hrs later I can confirm that many techniques have been changed by Boeing over the years. It was certainly true that originally the recommendation in the FCTM was not to use differential power in a turn, (I can no longer give a reference, the pages have long ago been consigned to the bin), but then at first a 2 engined approach and go-around was performed on the -400 as in the Classic with very late selection of gear and flaps and continued descent on the glidepath to increase speed in the g/a whereas now it is done much more like a standard approach/go-around. The only way to keep abreast of all the changes is to ensure your company gives you a fully updated copy of the Boeing FCTM.
Ground Operations
Copyright © The Boeing Company. See title page for details.
2.12 FCT 747 (TM)
Approach the edge of the taxi surface at a shallow angle until the outboard side of the wing gear wheels are near the edge. The lower outboard corner of the pilot’s forward window is a good visual reference for the outboard side of the wing gear wheels on the same side. The lower inboard corner of the pilot’s forward window is also a good reference for the opposite side wing gear wheels.
Note: Painted runway markings are slippery when wet and during turns nose gear skidding may occur. Due to the area covered, wet threshold markings typically cause pronounced nose gear skidding during runway line-up. In these conditions moderate differential braking may help in turning without nose gear skidding.
Turning radius can be reduced by following a few specific taxi techniques. Taxi the airplane so that the wing gear tires are close to the runway edge. This provides more runway surface to make the turn. If maximum turning capability is required, stop the airplane completely with the thrust at idle. Hold the tiller to the maximum steering angle, release the brakes, then add thrust on the engines on the outboard side. Only use the engines on the outboard side of the turn and maintain 5 to 10 knots during the turn to minimize turn radius. Light intermittent braking on the inside main gear helps decrease turn radius. Stopping the airplane in a turn is not recommended unless required to reduce the turn radius. As the airplane passes through 90° of turn, steer to place the main gear approximately on the runway centerline, then gradually reduce the tiller input as required to align the airplane with the new direction of taxi.
This technique results in a low speed turn and less runway being used. It does not impose undue stress on the landing gear and tires provided the wheel brakes are not locked during the turn. If the nose gear skids, a good technique is to apply the inside wheel brake briefly and keep the airplane turning with asymmetric thrust as needed. If the turnaround is planned on a surface significantly greater in width than the minimum required, a turn entry could be made, without stopping, at 5-10 knots speed, using intermittent inside wheel braking and thrust as needed. Wind, slope, runway or taxiway surface conditions, and center of gravity may also affect the turning radius.