Advanced disablement via keyswitch input

All,
   We have an advanced panel with void detectors and remote leds (which due to the existing cable are not physically connected and it is all done by programming so detector x activates beacon y on the loop)

Testing is awkward as we have to leave beacons enabled so when we test void detectors ALL beacons operate not just the one we're testing. I've been told i can connect a keyswitch to one of the internal inputs to disable all main beacons and leave the detector void beacons enabled however i would also like this keyswitch to turn the panel buzzer off - any ideas how?

Also if i turn the internal keyswitch to isolate all sounders, relays and selected beacons can i then put the panel into walk test with sounders and use this to activate only the beacons i want to test? Or will the walk test with sounders override the keyswitch disablement and set the whole place into alarm,

Advanced weren't sure and advised me to try it...