Here is the C# code to create a SQL Server Compact Edition (formerly known as
SQL Server Everywhere and SQL Server Mobile) programmatically with hostname
filtering:

       SqlCeReplication repl;

       try
       {
           // Instantiate and configure SqlCeReplication object.
           //
           repl = new SqlCeReplication();
           repl.InternetUrl = "http://www.websyncurl.com/sqlcesa30.dll";
           repl.InternetLogin = internetLogin;
           repl.InternetPassword = internetPassword;
           repl.Publisher = publisher;
           repl.PublisherSecurityMode = SecurityType.NTAuthentication;
           repl.PublisherDatabase = publisherDatabase;
           repl.Publication = publication;
           repl.Subscriber = subscriber;
           repl.SubscriberConnectionString = "Data Source=MyDatabase.sdf";
           repl.HostName = hostname;

           // Create a local SQL Server Compact database and subscription.
           //
           repl.AddSubscription(AddOption.CreateDatabase);

           // Initialize the subscription.
           //
           repl.Synchronize();
       }
       catch (SqlCeException)
       {
           // Handle errors here
           //
       }

For more info, see these topics :

http://msdn2.microsoft.com/en-us/library/ms171908.aspx
http://msdn2.microsoft.com/en-us/library/ms365205.aspx