They have a really thick shell, and when you get to the center, its a core of foam like compressed powder that as far as I could ever tell was unusable other than by oral route
Don't waste your time, if you really want to use concerta and/or it's your only choice, just pop about 60ish mgs or maybe a little more depending on your size, it wont be a rush but it'll speed your ass up over an extended period of time ;]