You don't need advanced features for that.
Make sure the joystick device (I.E. your throttle) is assigned to a joystick slot (under the "Joystick Options" button on the "General" tab of the VoiceAttack options window), then on the "Hotkeys" tab of the VoiceAttack options window click the ". . ." button next to "Joystick Button Recognition", check the "Enable joystick global buttons" option, press the relevant button on your device, choose the "VoiceAttack listens while buttons are down" "VoiceAttack stops listening while buttons are down" option, click "OK", click "OK".
Note that when this option is enabled, listening will automatically be suspended when VoiceAttack starts.