It would be nice if AH let us use analog controls for more things - I'd love to be able to use a slider to zoom in and out, for example, but I doubt we'll see that anytime soon.
You can, I did... First you have to make sure to calibrate the slider in game (like you do with the joy stick), then set it. I'm at work, so can't remember the exact setting, but it does work. The name of the setting makes sense, so just look around.
I set it to one of the wheels on my X52, it seemed to have more fine adjustment than the slider on the throttle.
ON EDIT... Just found the setting in another post, it's gunsight range increase/decrease...