How do I xml serialize a custom exception so it can be included as a
parameter on my webmethod?  See extra details below.

I have an audit web service which attempts to log exceptions to a database.

The web method looks like:

   <WebMethod(Description:="Log process message.")> _
   Public Function AddProcessMessage( _
           ByVal ProcessExecutionKey As Long, _
           ByVal AppEx As UserException) As Boolean

       ' Returns true if successfully logs the message and the AppEx log
flag will also be set to true.
       Return ProcessExecution.AddProcessMessage(ProcessExecutionKey, AppEx )
   End Function

This generates an error complaining about security permissions on the base
exception class, eg. properties such as 'TargetSite' can not be serialised.

Do I need to do imperative asserts or explicit demands or both.  If so could
you give me a code example that relaxes the security on xml serializing a
custom exception.

Thanks.