Not saying you need IS Boxer for this, just that you could accomplish this with IS Boxer.

Instead of two steps, executed on press and release.
Go with two steps, and the default 'execute a step on release only'.

Not sure that this will work with ctrl as the hotkey for the mapped key (toggle).
But you could set just about any key combination as the toggle hotkey.
So pressing Ctrl + T (for example), could run step 1 of the mapped key (enables the toggle), and pressing Ctrl + T again, toggles it off.
In effect, the same as Caps Lock or Num Lock.