The only way is to not bind the trim button in the game (it only understands sprung joystick logic) and then use either the hardware trim in configurator or, if you are using it, the hardware trim in TelemFFB.
If you have the trim button bound in the game it will double the inputs since it expects the joystick to be sprung and thinks you are going to let the stick go back to center after you have pushed the trim button.