Like Owltoid said, you can make your X-Keys do this with HotkeyNet. The basic syntax is:

Code:
<Hotkey F1>  // ANY X-KEYS KEY
   <Toggle>
      <Key A>
   <Toggle>
      <Key B>
   <Toggle>
      <Key C>
For more info:

http://hotkeynet.com/p/toggles.html

http://hotkeynet.com/ref/toggle.html