macro, keyboard interaction

Hello,
I write a macro for autocad and I generate a lots of objects(points) at
special coordinates on my drawing.
I choose own actions from userforms. One is to click on the
objects(points), get the coordinates from the object and create
text-number(counter) near the object coordinates.
My problem:
I want to break the action, if the user press a special key.
(e.g. backspace for declining one or more steps of the action)
It is possiple to evaluate pressed keys if a userform is shown
(keydown), but how can I break e.g. getobject (which waits for user
input) with a special key from the keyboard.
Thank You.
MfG
Axel