How can I map the F4 key's default functionality to trigger a key sequence rather than open Launchpad? (Mountain Lion) I will use the touchpad gesture to open Launchpad. I don't use Launchpad much.

I'd like to map the F4-key (which opens Launchpad) to send the Keystroke Command + Ctrl + Shift + 4 so I can use the OSX screenshot feature with it. 

BetterTouchTool does not allow me to do it because it does not recognize when I press this key. I can get BTT to recognize F4 (i.e. hold fn then press F4) but this is not ideal: I need the top row to mostly function the way they already do while also not requiring pressing fn to take a screenshot.
This is more or less exactly what I wanted. 

http://kevingessner.com/software/functionflip/

Works perfectly and no BTT is needed for setting the keyboard shortcut (Do it through Keyboard -> Keyboard Shortcuts in System Prefs)