kill switch? u mean the stuttering, on-off sound he got? if that is the one, here's how he does it in ratm.
he uses a guitar with 2 volume control, one for each pick-up. u turn the volume on one of the pickups all the way to zero/off. the other one u leave all the way up/on. when u want to get the effect, use the 3-way switch and quickly switch between the 2 pick-ups. that switching gives u that stuttering effect as u are constantly switching between the "on" and "off" p/ups. u get it?
some people actually put an on-off switch on the guitar, but that needs mods. of course if ur guitar has got 1 volume only, then that might be the best way...
its good if ur "switch playing" is in-rhythm/in-synch with the beat of the song. it sounds better.