I just tested with Copter-4.2 (currently in beta testing) in the simulator and I was able to change both the radius and the angular velocity. The slighlty odd thing about the angular velocity is that it uses the roll stick and right means faster, while left means slower. The odd thing about this is that by default the vehicle moves in a clockwise direction so it seems a bit backwards to me. BTW when changing direction you must temporarily leave the roll stick in the neutral position.
@rmackay9 : Just back from test flight (using 4.2 RC2) and I think it worked as you described it. However the change rate is that small that it is hard to me to see something happen at all. Can I increase the change rate? Are there parameters for that? (And what you mentioned already; can we swapp roll left and right such that it behaves more naturally?)