Set log message within script task

I have a script task in my control flow that does some validation checking. If one of those checks fails, I want to fail the task and send an appropriate message via email. I've accomplished this by updating a package that is then used as the source for the email message.

However I also want my message text to appear in the package ...Log.xml file. Currently it only says that the script task returned a failure result. There must be some way to do this, and I hope some guru out there can help me.

Thanks,
Phil