The MS14A hack is to the dusk dawn sensor circuit. It is one Unit Code higher than the motion sensors address.
So setting the motion unit code one number lower would give you the On and Off to the address you desired. Using the modified dusk dawn circuit. The motion sensor would still be active with the mod. So it is possible it could still send motion detection messages.
DS12A is a security type sensor and sends security messages that do not have a House Code and Unit Code address in the message.
Do you have the On Alert plug in for AHP? It allows you to add DS12A and DS10A sensors to your setup.
The WGL V572RF32 can also receive a DS12A or DS10A RF signal and map it to a standard X10 address.
The DM10A referenced in your second link. Was the outdoor motion sensor for the Robodog Barking Alarm Console.
http://kbase.x10.com/wiki/Outdoor_Motion_SensorI have a DM10A, strange beast. Only sends On commands never an Off after a time out.