If u search gx160 manual on google or on the honda site there is a wiring diagram for the killswitch in there. There pretty complicated electrics wise compared to other briggs engines n stuff.
look on the side of the coil there should be a small wire connected to it... run this wire to one post of the switch (push button, lever, well anything n.o) and the other post to the ground (engine's block) thats it...
have a look at this. its the same basic idea, if you ground the wire(ie thouch it on any part of the block) then the spark gets cut. the setup on the clone i took apart was exactly the same as this(you ground wire 1 and the spark is cut) so if you follow everything in that then you should be fine(ignore the bit about wire 2 and the carby stuff though).