They are reversed in your preference perhaps
To make changes, go to extreme\_ex_zoom.gsc -- just look for these 2 lines
if(self useButtonPressed() && iZoomLevel > level.ex_zoom_min)
<-- Change useButton to meleeButton if(self meleeButtonPressed() && iZoomLevel < level.ex_zoom_max)
<-- Change meleeButton to useButtonAnd now you get your preference