Hi Franx;
I'm using just such an animal. In the game options you can assign commands to your joystick....with limits. I've tried to assign the 'rudder' function on my rig to move the turret but I'm not sure that can be done.
As you probably know already, the hat switch gives you basic control of the vehicle's movement. When using the gunner's sight, you can traverse side to side or up and down by moving your stick. Other than that, I'm not sure what else you'd want. Machine gun is trigger button 1, main gun is trigger button 2. By default, other joystick buttons are used for ammunition selection, I think.
Hopefully someone with more experience than me can step in on this.
Cheers,