need help with L4 switch mod (2 stage McE2S)

I just got a McE2s from the sandwich shoppe and was intending to put it in a Z57 / L4 tailcap. But I can't seem to get it to work. The McE2S was fully assembled and came with a black retaining nut. Where does this nut go for an L4? In from the battery side, or the boot side? Does it need to be filed down? I have seen conflicting posts on this. I just got the McE2s in the mail today, so it should be the latest one. The problem seems to be no matter how I assemble this thing, the swtich does not click to switch the light between high and low. I screw it on and the light comes on high and thats it. I am snapping the switch into the black retaining crew on the side away from the spring on the McE2s (on the button side). Any help appreciated.