Short but good article on adding events to your SSIS Scripts by Colin Kirby. I use the firing of OnInformation events in more complex scripts to assist in tracing the operation of the script for debugging.

SSIS: Event Firing with Script Tasks

I recently worked on a project where I was unable to use breakpoints in the scripts due to the configuration of the customer's computers. By using various script events, I was able to track the progress of my scripts and determine where I had an error.