An FIA kill switch will have 6 poles. The two main ones and 4 smaller switching poles. All are linked and open and close together.
The main switch will break the battery positive side ahead of any functions, so everything should go dead.
Bank one of the smaller side runs from downstream side of the main battery supply back to an earth point, but must include a 3 ohm resistor which discharges anything coming off the alternator when the switch is opened.
The second bank intercepts the feed from the ignition switch to the coil pack or ignition relay, acting as if you are turning off the ignition.
If you are wishing to maintain push button start, which I assume is the question, you will have to find the ignition relay that the starter button and logic circuit is operating and break the feed at the output of that relay.
