Writing to the security audit log when using forms authentication?

I am writing a secure MVC application that is using forms authentication against user accounts maintained in a database.  We are not using the membership provide because we are going to be using some fairly complex adaptive authentication.  One of the requirements is that we log all authentication success and failures to the windows security event log.  We also need to log any authorization failures.  I have been searching around online an on MSDN and have not found any information on how to do this.
Because the actual authentication logic will be on a separate server behind a firewall, we don't necessarily need to make these log entries on the web server from with asp.net.  We can make them from the .net windows service that actually does the authentication.
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