Perhaps I've been the one to misunderstand, for it seemed to me the resistor mentioned was in series with the line (NC sensor). If it is in parallel (sensor normally open), things get more complex.
In THAT case, one might try three resistors, each about one third the total value, one in series with each wire at the controller and one across the sensor, serving the same function as a single parallel resistor at the sensor. This would still give 280 or 330 ohms series impedance for RF, again, more than a ferrite at 40 meters, at the alarm controller. I don't know if the 660 ohms or son "on" resistance would still let a sensor trigger the alarm, though. Might show up as tampering, not an alarm. You might have to use lower values for the series resistors. Could be a cheap way to build immunity into controllers, though.
Cortland