It has been a long time since I have seen my 0-4-0T so I can't be real specific. I assume you have the 0-4-0T. You would need to cut the coal bunker off the rear of the cab. Then find a place to drill and tap a 00-90 screw into the bottom of the engine. Then cut the head of the screw off to leave a post for the drawbar to go.
The coal bunker is the part that sticks out behind the cab in the side view. When you cut off the coal bunker, you will lose the coupler mount. Where you are talking about mounting the pivot for the tender would be the right place.