Here are some bad photos ... still, better than no photos.
I've wrapped a velcro cable tie around the shifter knob, with the tail running through a piece of heat shrink tubing to hold the switch. It rotated a bit on the knob at first, but hasn't moved since it was pulled tighter.
I used a second cable tie to hold the top of the shifter boot in place, where the cable pushes past.
The indicator light (below the vacuum gauge) reminds me when the injectors are off, so I can use engine braking down steep hills.