Alert messages to client computers from Altiris based on SNMP Traps

I have a network device (Poseidon2 3266), from which I'm sending traps to NS. Alert detail is in attachment.

If these variables are: inpName=EZS AND inpAlarmState=1, I need to display popup alert window (e.g. Alarm activated!) on client computers (with Altiris agents).

If the SNMP::SendingHost is e.g. 10.20.30.1, I need to display the alert message on all computers in the same subnet 192.20.30.0

I made some experiments in Alert Rule Settings > Task rules, but have these problems

- how can I work with mentioned variables inpName, inpAlarmState, while they are in alert desciption

- how can I create task for displaying alert message? (I heard something about DisplayBalloon method...)

- how can I target the task to run in the specific subnet?

Thanks for any help.