A very, very badly hacked together executable that can turn on and off function keys on my Retina MacBook Pro 15" (Mid-2012). What I'm saying is that it WORKS4ME and with ControlPlane.
At least it does not use GUI scripting with Applescript to accomplish this goal.
Standard Function Keys
Note: You may need to toggle the state on or off explicitly before toggle previous state invokation can work.
Note that the original F9-F11 keys are most likely still bound to the Expose stuff. This simple program does nothing to address that.
The Keyboard Preference Pane does not update with values set by this tool while running.
The Schism tracker code is GPL2 but wow a bunch of it looks to be the product of disassembling the Keyboard Preference Pane anyway like me. Regardless, this project could be GPL2.