The Challenger and Extreme have 3 channels. They are throttle, pitch and steering (yaw). The V-Tail can handle pitch and steering just fine. Pitch is implemented by deflecting both ruddervators (tail flaps) up (or toward the centerline) at the same time for up pitch and vice versa. Steering is implemented by deflecting one toward the centerline and the other one away from the centerline. There are some real airplanes that have this configuration, such as the Bonanza, but they are rare.

I believe the Scout implements steering a little differently by deflecting only one ruddervator at a time. This is really a combination of steering and up-pitch which helps maintain altitude in the turn.

I just bought a Challenger.