howdy gents :)

So I'm starting my first UAV with a v tail and will need to enable the rudder and its mixing, I was wondering if anyone could help me out or give me some tips, I'm using a global hawk model from hobbyking. It is MONSTROUS which is good because my last UAV didn't have enough power or lift /: anywho I will be using a Vtail mixer after the Ardupilot 1.4, do I need to flip a switch on the Oilpan, or is that only if I'm using Elevons? I just need to activate the rudder, the mixing will be done after the Ardupilot has had its way with it.
Thanks
George