there is a command line tool for patrol agent named patrolcli which can connect to agent and run psl commands which can trigger external scripts.
user of patrol central console (or classic console) can trigger scripts via standard patrol agent's psl or OS script launch by context menu
another option is to create own c-api based tool to launch scripts
I believe you can use SENTRY Monitoring Studio to build a script-based custom monitor in PATROL.
As someone else mentioned, you can use PatrolCli to execute ad hoc scripts, however, there is nothing
inherent in that methodology that allows you to associate the script with a custom parameter (as can be
accomplished using ProactiveNet Script Monitor).
Alternatively, you can write a custom KM, however that requires development using the PATROL
Developer Console. I understand that the SENTRY Monitoring Studio has a wizard that allows you
to do something on the PATROL side similar to what can be done using ProactiveNet Script
Monitor. However, I've never used it.