Script: Act upon double key press (with modifier)

[d-t-o]

I'd like to map

cmd-tab -> operation1 cmd-tab-tab -> operation2 cmd-tab-tab-tab -> operation3

My problem is that not the second pressing of tab fires the action but the release of the cmd key. I fail to see how a karabiner script would look like that allows me to do this (basically count tab-presses and evaluate upon cmd release). All examples I've found that do something with multiple key presses involve a delayed action, but in my case there's no 'timeout' for the action to fire.

Is this possible with karabiner at all? Or does anyone know any other way of achieving this?