public static void MyMethod(
   ServiceDescriptionBaseCollection myServiceCollection)
{
   Type myType = myServiceCollection.GetType();
   if (myType.Equals(
      typeof(System.Web.Services.Description.ServiceCollection)))
   {
      // Remove the services at index 0 of the collection.
      ((ServiceCollection)myServiceCollection).Remove(
         myServiceDescription.Services[0]);

      // Build a new Service.
      Service myService =new Service();
      myService.Name="MathService";
      XmlQualifiedName myXmlQualifiedName = 
         new XmlQualifiedName("s0:MathServiceSoap");

      // Build a new Port for SOAP.
      Port mySoapPort= new Port();
      mySoapPort.Name="MathServiceSoap";
      mySoapPort.Binding=myXmlQualifiedName;
      SoapAddressBinding mySoapAddressBinding = new SoapAddressBinding();
      mySoapAddressBinding.Location = "http://localhost/" +
         "ServiceDescriptionBaseCollection/AddSubtractService.CS.asmx";
      mySoapPort.Extensions.Add(mySoapAddressBinding);

      // Build a new Port for HTTP-GET.
      XmlQualifiedName myXmlQualifiedName2 = 
         new XmlQualifiedName("s0:MathServiceHttpGet");
      Port myHttpGetPort= new Port();
      myHttpGetPort.Name="MathServiceHttpGet";
      myHttpGetPort.Binding=myXmlQualifiedName2;
      HttpAddressBinding myHttpAddressBinding = new HttpAddressBinding();
      myHttpAddressBinding.Location = "http://localhost/" + 
         "ServiceDescriptionBaseCollection/AddSubtractService.CS.asmx";
      myHttpGetPort.Extensions.Add(myHttpAddressBinding);

      // Add the ports to the Service.
      myService.Ports.Add(myHttpGetPort);
      myService.Ports.Add(mySoapPort);

      // Add the Service to the ServiceCollection.
      myServiceDescription.Services.Add(myService);
   }
   else if(myType.Equals(
      typeof(System.Web.Services.Description.BindingCollection)))
   {
      // Remove the Binding in the BindingCollection at index 0.
      ((BindingCollection)myServiceCollection).Remove(
         myServiceDescription.Bindings[0]);

      // Build a new Binding.
      Binding myBinding = new Binding();
      myBinding.Name = "MathServiceSoap";
      XmlQualifiedName myXmlQualifiedName = 
         new XmlQualifiedName("s0:MathServiceSoap");
      myBinding.Type=myXmlQualifiedName;
      SoapBinding mySoapBinding = new SoapBinding();
      mySoapBinding.Transport = "http://schemas.xmlsoap.org/soap/http";
      mySoapBinding.Style = SoapBindingStyle.Document;

      // Create the operations for the binding.
      OperationBinding addOperationBinding = CreateOperationBinding(
         "Add", myServiceDescription.TargetNamespace);
      OperationBinding subtractOperationBinding = CreateOperationBinding(
         "Subtract",myServiceDescription.TargetNamespace);

      // Add the operations to the Binding.
      myBinding.Operations.Add(subtractOperationBinding);
      myBinding.Operations.Add(addOperationBinding);
      myBinding.Extensions.Add(mySoapBinding);

      // Add the Binding to the Bindings collection.
      myServiceDescription.Bindings.Add(myBinding);
   }
   else if (myType.Equals(
      typeof(System.Web.Services.Description.PortTypeCollection)))
   {
      // Remove the PortType at index 0.
      ((PortTypeCollection)myServiceCollection).Remove(
         myServiceDescription.PortTypes[0]);

      // Build a new PortType.
       PortType myPortType = new PortType();
       myPortType.Name = "MathServiceSoap";

      // Build an Add Operation for the PortType.
       Operation myAddOperation = new Operation();
       myAddOperation.Name="Add";

       // Build the Input and Output messages for the Operations.
       OperationInput myOperationInputMessage1 = new OperationInput();
       XmlQualifiedName myXmlQualifiedName1 = 
          new XmlQualifiedName("s0:AddSoapIn");
       myOperationInputMessage1.Message = myXmlQualifiedName1;

       OperationOutput myOperationOutputMessage1 = new OperationOutput();
       XmlQualifiedName myXmlQualifiedName2 = 
          new XmlQualifiedName("s0:AddSoapOut");
       myOperationOutputMessage1.Message=myXmlQualifiedName2;

       // Add the messages to the operations.
       myAddOperation.Messages.Add(myOperationInputMessage1);
       myAddOperation.Messages.Add(myOperationOutputMessage1);

       // Build an Add Operation for the PortType.
       Operation mySubtractOperation = new Operation();
       mySubtractOperation.Name = "Subtract";

       // Build the Input and Output messages for the operations.
       OperationInput myOperationInputMessage2 = new OperationInput();
       XmlQualifiedName myXmlQualifiedName3 = 
          new XmlQualifiedName("s0:SubtractSoapIn");
       myOperationInputMessage2.Message = myXmlQualifiedName3;
       OperationOutput myOperationOutputMessage2 = new OperationOutput();
       XmlQualifiedName myXmlQualifiedName4 = 
          new XmlQualifiedName("s0:SubtractSoapOut");
       myOperationOutputMessage2.Message = myXmlQualifiedName4;

       // Add the messages to the operations.
       mySubtractOperation.Messages.Add(myOperationInputMessage2);
       mySubtractOperation.Messages.Add(myOperationOutputMessage2);

       // Add the operations to the PortType.
       myPortType.Operations.Add(myAddOperation);
       myPortType.Operations.Add(mySubtractOperation);

       // Add the PortType to the collection.
       myServiceDescription.PortTypes.Add(myPortType);
   }
 }