awesome, thanks alot. your exact settings didn't work on mine, but when i added your code
<action name="v_rollleft" onPress="1" onRelease="1" onHold="1">
<key name="a"/>
<key name="joyrot_z"/>
</action>
<action name="v_rollright" onPress="1" onRelease="1" onHold="1">
<key name="d"/>
</action>
to helicopter, that worked.
for those who were wondering, notice how Malecite (and now I) included <key name="joyrot_z"/> for the action "v_rollleft" but not for "v_rollright". that seems to be the necessary trick.
also, if you're using an xbox360 controller like me, you can use joyaxis_x (left thumb joystick) instead of joyrot_z (triggers). personal preference though.