Multi DataBase server connection in Asp.net MVC 3

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C#

MVC

NHibernate

I am using 'Bootstrapper' class inside the Method is:

private static void ConfigureNHibernate()
        {
            NHibernate.Cfg.Configuration cfg = new NHibernate.Cfg.Configuration().Configure();
            cfg.Properties["connection.connection_string"] = ConfigurationManager.ConnectionStrings["DefaultConnectionString"].ConnectionString;
           
        }

And in Web.config:

<configuration>
<configsections>
    <section name="dataConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings, Microsoft.Practices.EnterpriseLibrary.Data" />
  </configsections>
  <connectionstrings>   
    <add name="sql" connectionstring="Data Source=192.168.3.250;Initial Catalog=MNTPayroll;User ID=sa;Password=hbd123@2" providername="System.Data.SqlClient" />    
  </connectionstrings>
  <dataconfiguration defaultdatabase="sql" />

I want to use multi-DataBase server. how can I do this and how can I use the second or third Database connection string to my application when to access...