I believe if you are at talking about the FOV hat on top of the joystick in this sort of fashsion...
http://imageshack.us/photo/my-images...ystick0mm.jpg/
They are normally the axis's 5 and 6 and typically only return -1,0,1 values. In order to make it a button function just take the output of the axis and compare it to see if it is greater than say '.99'. Or at least that's how they function on our Saitek Joysticks.