HDB has a variety of top clamp layouts available.
I selected one that has space for two powerlets and four switches.
I'm going to use the four switches for:
fan override, headlights off/on, headlight high/low and heated grips off/on
The pushbutton switches simply fit in the holes (which are designed for the fit)
and then the rubber waterproof caps screw on to hold the switch in place..
...to be continued.