Basically, all the throttle cut button does is put the throttle servo to full down stick and full down trim. It obviously does not move the throttle lever, but it does this electronically.

So to set this up, you need to make it so that when you are idling, your trim setting is in the middle or upper end of the trim travel. Then just go to the programming menu and make sure the throttle cut function is active. Then when you push the throttle cut button, it will take the trim down to the lowest setting. When you release the button, then it will return the trim to where you had it earlier.