Como usar MySQL e MSSQL juntos na fonte de dados grails?

environments {
    production {
        dataSource_authentication {
            pooled = true
            url = "jdbc:mysql://yourServer/yourDB"
            driverClassName = "com.mysql.jdbc.Driver"
            username = "yourUser"
            password = "yourPassword"
            ........
        }
        dataSource {
            pooled = true
            driverClassName = "com.microsoft.sqlserver.jdbc.SQLServerDriver" 
            dialect = "org.hibernate.dialect.SQLServer2008Dialect"
            ........
        }
    }
}