Set sensorvariable value on server only (without transmit)

Refer : https://forum.mycontroller.org/topic/146/how-to-set-sensor-value-with-javascript/6

I have "virtual"/"fake" sensor variables which calculate percentage and litres based on the distance sent. I need to be able set those in javascript without MyController sending a payload. This is especially important with ACK enabled as when ACK is enabled it causes more issues.

Thanks
