Tanks for answering!
I wasn’t clear enough. Of course I have already assigned a shortcut for that, in my case ‘Y’.
What I want to do is: Have Auto-Shift enabled all the time, then have it disabled WHILST
pressing another Key (Modifier), then release this Key to go back to Auto-Shift.
So I don’t have to toggle the Shortcut for Auto-S all the time, it’s always on and only temporarily disabled…
Sorry, I hope ist doesn’t sound too confusing 
Regards, Oliver