Does anyone know if a glue in broadhead adapter like THESE (http://www.3riversarchery.com/images/large/BA-X.jpg) are made to accept the internal screw in weight systems.
Never seen one. What I would do is find a regular insert that fits inside (tightly) trim off the shoulder and glue it in.
You may need to run an 8-32 tap right though the insert so the threads are available at the back end.