"A ball ends up between 3man goalie and edge of goal ready to drop"
To me it seems that the only way out of this situation is attempt to move ball out of reach and have an intentional dead ball penalty. Others (ok everyone else I have spoken to thus far) say you can accept a "time of possession" penalty.
1. That can not be the original intent of time of possession rules and you can't call a time of possession penalty on yourself.
2. Reaching in to stop a goal results in a goal -and its hard to argue that's not the end result