double click "shift button" to activate caps lock in mac os x lion???

My apple bluetooth keyboard's capslock recently broke. (i am aware of the sensitivity issue, this is not it, my button is completely crazy and just keeps turning caps on and off randomly, so i turned caps lock off from the system preference)

However, I was wondering if there's another solution to this by simply pressing the shift button twice to activate caps lock? that way it would be consistent with the IOS keyboards. I'm currently using "better touch tool" but it wouldn't let me press shift key twice as a keyboard shortcut :(