Yes - but there will be a little wiggle room. They are 15/16" - so smaller than a standard pushbutton hole. Plus, there are little orientation pegs to keep it from spinning that will need a small hole punched out for. If you crank it down, it should cover the hole just fine. I have some that I haven't gotten around to mounting yet, just because it's too freaking cold out now...
** Edit **
Here's some info from Randy:
Ok, some dimensions:
First, it's not the same diameter as a standard pushbutton hole. The threaded portion of the body is 1" long and .925" diameter, or made for a 15/16" hole. I think 1" would be fine.
The outside dims are 1.3" wide, by 1.96" tall. The actual button face is .938" wide by 1.588" tall.
They also have orientation pegs to keep them from spinning, so I guess they could be used with existing holes just by putting the smaller peg holes above and below the existing pushbutton hole and then tightening the nut down. I don't think it will go anywhere, and it should cover everything fine.