To do by the book, it is a two-step process. In one part of the manual, it with the handlebars and the handlebar bracket off to use special tools on the steering nut and locknut, tightening them to a specified torque. In another area, it does not mention using special tools on the nuts but, to tighten said nuts until until a spring pull-scale attached adjacent to the inside edge of the outer handgrip flange indicates a tension of 200 to 500 grams when the handlebar first starts to move. Unless one uses trial and error, taking the handlebar and bracket off to use the special tool and reassembling to make the spring-scale measurement, the only way to do it would seem to be with the drift/screwdriver and hammer tap method. After I had done mine I decided next time I would do some math to take the specified pull (200 to 500g) and get a torque by multiplying it times distance to center of steering stem, measured perpendicular to the steering stem axis. Then, find a way to attach the spring scale to either the tire, a fork, etc, measure that distance to said centerline and divide that number into the previously determined torque. This should give the spring scale pull needed at the new point of attachment to achieve the specified reading at the handlebar. Then, with the handlebars and bracket off, the special tools could be used to get the desired pull measurement. I just don't like the idea of beating on those two nuts. Several methods have been used to create special tools. Here are mine:
[attachment=0:3f8p8ix9]DIY steering adjustment sockets (2).jpg[/attachment:3f8p8ix9]