hi there
you need to use (two) free mixers
one for rudder elev, one for rudder aileron
but it's not an exact science as different air speeds require different amounts of mix.
also, the mix is not linear, so the right amount for a simple K/E pass will not be the correct mix for a K/E loop.
everyone that I know leave the mixes on all the time but some may prefer to switch it on and off.

hope this helps

piroflip