Although you can't disable the 150 Hz. NATO RX squelch by software (this still needs to be done using the mod described in the article by Jacob PE2CJ) It is possible to disable the transmitted pilot tone using a programmer command.
A fellow OM told me this tone could be heard during a QSO so i took a look at the signal using a RTL stick and HDSDR:
|150 Hz pilot tone active|
This is the result when setting the channel's sub-tone value to 'N' in the Arduino Cougar Programmer:
|150 Hz pilot tone disabled|