The Extension Tool (described in Extension Tool for Custom Scripting) can be used to report custom events to the Event Log by calling the report(IEvent) method of the given com.parasoft.api.ScriptingContext object.
Here is a Jython example:
from com.parasoft.api import Event def test(input, context): context.report(Event("Here I am!"))
See com.parasoft.api.ScriptingContext and com.parasoft.api.IEvent in the Extensibility API Javadocs for more information. Choose Parasoft> Help, then look for the book titled "Parasoft SOAtest Extensibility API".