I've been putting the buttons on further than the little guide tube that comes with them. Now they bottom out on the top of the mod before I can press too far. Don't mash it on too far or it will bottom out before it makes contact, with a little playing you can get just the length of throw you want.
That's just what i do. I prefer it that way because it makes the button not quite so tall and i don't notice that button against reo grind feeling when I push it at an angle.