A customer question I can't answer. Can anyone help?

I'd like to prepopulate some fields when we create new cases. I've come across a few ways to do that for simple standard fields and for custom fields, but one of the fields that I want to work with is a Long Text Area, and those seem to be more difficult. Is there a recommended way to prepopulate a Long Text Area field? Is it possible to do it by pulling in the text from an object somewhere, such as the contents of a Content record, or perhaps a static resource?

thanks!

Mysti