al_set_mouse_axis
bool al_set_mouse_axis(int which, int value)
Set the given mouse axis to the given value.
The axis number must not be 0 or 1, which are the X and Y axes. Use al_set_mouse_xy for that.
Returns true on success, false on failure.
See also: al_set_mouse_xy, al_set_mouse_z, al_set_mouse_w