I tried arnehs way of trimming but it didn't work for me as I don't have any FFB devices.
For trimming I also use a combination of in-game trim for the rudder pedals (not connected to Cougar) and the trim function of the HOTAS.
/P LOCK (JOYSTICK, LASTVALUE) TRIM (JOYSTICK, TO_CURRENT) /R Trimmer DLY(60) TRIM (JOYX, 0) TRIM (JOYY, 0) UNLOCK (JOYSTICK)
Usage:
Hold the button, center the stick, release the button, center the pedals.