I think maybe I have it.
Install a 2-way mechanical switch, which is basically a SPDT switch. The “UP” position throw is wired full-time HOT, the “DOWN” position throw is wired to the output of a switch module (other side of it also connected to full-time HOT) set to match the sensor and transceiver, the center pole goes to the overhead room light.
In the “UP” or “ON” position, the overhead light illuminates and does not care what occurs at the disconnected other throw position. In the “DOWN” or “AUTO” position, the overhead light is controlled via the sensor. Upon turning the mechanical switch down to “AUTO” - yes, if the sensor had already turned on the X10 switch, the light will NOT go dark, but will do so after the sensor delay times out. If the sensor was not tripped, the overhead light will go off immediately.
Yes, I will have to get creative in placing both switches in a single-gang box, but they do make boxes with extra room to one side for more “junk”, even though they take up one gang position.
Solution !? Sensor lights indoor room lights, but does not affect my “override” ON switch position.