Mark Overmeer sent me a solution:

return
  +{ PolicyException =>
       { faultcode   => pack_type(SOAP11ENV, 'Server')
       , faultstring => 'policy exception'
       , detail      => 
          { messageId => $error_code
          , text      => $error_message
          , variables => [ $error_code, $error_message, ]
          }
       }
   };
[download]

Thanks Mark :-)