Martin, reading your posts you are using the older version 2 Cockpit Sx which does not have the ability to reassign channels (except in Easy where you can reassign the 2nd aileron channel) so there is no spare channel for the sensitivity.
To use the Wingstabi, you could make a new model using the easy template and then put the ailerons on a Y lead on one channel. You would have to do a mix to get the flaps to work on 2 servos or use a reversing Y lead.
Then you could use the 3 position switch or slider to operate the sensitivity channel.
