I used Logitech Rumblepad. It has two "sticks" and a slider, which gives you 5 proportional channels. You just need to re-assign the sticks to proper channels in the sim.
Works fine. The only little problem is that the throttle stick also has a spring, which returns it to the central (mid-open throttle) position. You may try to fool the sim by calibrating the throttle channel over its half-range: from the middle up.