I'm no expert, either.. but a couple of ideas:
1. If the plugin had a numeric entry capability

then you could enable quick bypass on the panel (in *23) and have a scene that initiaties a quick bypass (code + 6 + #) before arming
2. I've never tried it, but there is a luup action where you can bypass all. The code would be something like:
luup.call_action("urn:micasaverde-com:serviceId:VistaAlarmPanel1","BypassZones",{Zones="all",PINCode="1111"},Partition_Device)
Obivously substitute your pincode - I haven't tried this, but it should work (and it uses the quick bypass in the function, so you need to have that enabled on the panel regardless).