HELP, NEEDED WITH JR and TAILESS Plane
 

I have got a WESTON UK PLANE WHICH IS BASICALLY A DELTA plane with no rudder.

My question is, how do I setup my JR PCM9 Radio, which channels do the two elevator servos go into, is there anything I need to activate this setup.
Its probably easy, but I got my dumb head on, and cant sort it out. Basically the elevators act as ailerons as well, so I need to mix these some how. i did it a particular way but could not seperate the ATV on Elevator and Aileron??? I must be doing something wrong???

Thanks