Sorry for the delay. If the Eaton UPS logs an event to the application event log then it should be easy to setup a filter rule to get notified when the UPS triggers an alert. Can you open the EventSentry Management Console and view the Application event log to see if you can find events that are logged by the UPS? The event source should contain the word "Eaton".
Once you have confirmed that events are written to the event log, we can send you further instructions on how to setup a filter rule. Normally it's enough to just right-click the event and selecting "Add Include Filter".