Can I make the Launchpad key (F4) on my new Macbook Pro toggle Mission Control instead?
What you want is FunctionFlip:


You can individually choose which keys you want as standard f-keys and which you want as the Mac-specific functions. In your case, "flip" the F4/Launchpad key, then assign F4 to launch Mission Control.

The only caveat is you cannot use both FunctionFlip and BetterTouchTool, as the developer of BTT points out.