This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Why use a FileAppender? Just write a custom appender and have that communicate with your code.
There is no way to get Hibernate to do this for you. Doing anything (beyond logging) with the SQL generated by your JPA implementation kind of doesn't make sense which is probably why there is no out the box way of doing it.