Measure the length of the cords attached to the pushbutton switch and subtract one inch.
Open the book to the first page. Halfway down the length of the binding, measure out this number and mark it with a pencil.
Lay the pushbutton switch on the page with the cords running toward the binding and draw around the entire thing, cords and all.
Use your X-acto knife to hollow out a space large enough for the pushbutton switch to sit in snuggly. Make sure you don't cut too deep. The button needs to stick out 1/4" above the level of the first page in order to work.
Where the pushbutton switch cords meet the binding, cut a hole large enough to pull an electrical cord through.