Daniel
When I started working with the Event UI, I found everything I needed in the SOI guide. Starting from p596 of the CA Service Operations Insight - 4.0 CU1 guide, Event Management is explained. Event Properties and Values on p621 onwards, will help you achieve what you require. The fn:Parse() is explained on p623.
One of the most important things to remember, is the following:
Use the right-click menu to automatically populate pattern fields with the appropriate property names and enumerated values. (p621)
Once you use the right-click options, the only thing you need to do, is find the correct regex. You can do some really 'funky' stuff with the Event UI.
Have fun with the Event UI......I know I do