not sure how the programing cable works and what the interface is on the computer but...
typically you plug the right side into the aileron port and left into Aux1. Then change your wing type to "flapperon" in the programing. There should be the ability to set the amount of flap you want for take off and landing. it should automatically set this to your flap switch. you may also need to mix in some down elevator depending upon how much flap you add.
I agree with @mrjdstewart, it's best to use a preprogramed mix if one is available.
A word of caution, flaperons should only be used with full length ailerons.
With ailerons that only use the outer half of the wing, flaperons will create a nasty wing stall.