You can use a pose file to run a Python script:

{
    version
    {
        number 6
    }

    runPythonScript ":runtime:pathscript.py"
}

And you can combine this with all other pz2 tricks.

runPythonScriptEx apparently allows you to pass an argument to the script: runPythonScriptEx "runtime:path:to:script.py"myargument

where in the script, sys.argv[1] == 'myargument'