The switch is near the pivot of the clutch pedal, and you can push it in by hand, too.
But since it has to be activated for the SEE to start in the first place, it most likely either works or is bypassed. At one point I thought that the splitter didn't work on mine, or that the rpm difference was minute, until one day I did push the clutch in all the way while driving - after reading that the switch had to be activated.
Since I try not to use the clutch any more than necessary, and don't push it all the way other than to start, for all practical purposes my splitter doesn't work, either.
It could be that your driving style is like mine when it comes to clutch use, and that you just need to "stomp" on the pedal instead of pushing it normally, part way.