Skeet,
After installing mine, I weighed the odds between testing on the centerstand and manning up and playing crash test dummy...
So I tested mine on the centerstand, holding it back to make sure it couldn't vibrate off the stand and take off.
Mine engaged, but had to be in 5th gear and at least 35 mph.
However, without the friction and load of the road against the rear wheel, it will rev up and down, repeatedly. But, as Brian stated, it proves it's engaging.
When it does this on the centerstand, it's merely exceeding the set speed, then slowing, then trying to reacquire. Once it passed this test, I went for a ride and it worked perfectly.
That was over 2 years ago, still works perfectly.
That's how I did mine.
YMMV, though! Be safe. The key is it has to be engaged at 35 mph or faster, and in the higher gear. Hope this helps.
Bob