Mabinogi creates an application level keyboard hook. I'm 95% sure that these application level hooks override global hooks, with the exception of ctrl + alt + delete.
For those who don't know, all Mabinogi hotkeys are based on an application level keyboard hook. I know they're not global because pressing my F1 hotkey outside of the game doesn't activate my F1 action, but rather, opens up help (for most programs). However, the hiding program you're looking for would need to set up a global hook. That means that you could use that hotkey even if that program is not the active window.
AHK did something, somehow, that set global hooks that overrode Mabinogi's application hooks. AutoIT doesn't seem to do the same thing. I used to be able to write AHK scripts that use F1-F12 as hotkeys, and when pressed, it'll trigger then AHK function and NOT what I have it assigned to in the game. Now, for AutoIT, that doesn't work anymore.
I really liked what AHK did. I also wonder how they did it.