Express; either way you go, you will need a milling machine. James Jones' method would be quick to set up for a once-in-awhile installation. Sighter's would be better if you do very many of them, and once built, the lathe jig would be the best and quickest overall.
I've thought about the possibility of doing a one time job by hand. It would be possible to hog off most of the knob on a grinder and very very carefully finish up the major diameter with a belt grinder and a file, stopping a lot to caliper the diameter, concentricity, and to avoid tapering the tenon. Getting a true start on the threading die wouldn't be easy, either, but with a die stock and a lot of care, it could be done. No matter how careful you are though, it wouldn't be as good as doing it in a machine.
Good luck, Tom