Method to convert simultaneous key chord / letter key combo into another key?

I'm looking for a method to make simultaneous key presses trigger another, e.g. for the keys "w", "e", "f", pressed simultaneously, to trigger another key press, say, "Control-Alt-Escape".

My ultimate goal (in case it makes a difference) is to make a vim-like XMonad configuration: that is, I would like to use the simultaneous key chord "w/e/f" to "escape" into "Normal Mode" (a XMonad.Actions.Submap (submap)).

So far, I have tried xbindkeys but have not figured out how to specify a key chord of that sort.

Thank you for any suggestions beforehand.