// Create a WSHttpBinding and set its security properties. The
// security mode is Message, and the client is authenticated with 
// a certificate.
EndpointAddress ea = new EndpointAddress("http://contoso.com/");
WSHttpBinding b = new WSHttpBinding();
b.Security.Mode = SecurityMode.Message;
b.Security.Message.ClientCredentialType =
    MessageCredentialType.Certificate;

// Create the client with the binding and EndpointAddress.
CalculatorClient cc = new CalculatorClient(b, ea);

// Set the client credential value to a valid certificate.
cc.ClientCredentials.ClientCertificate.SetCertificate(
    "CN=MyName, OU=MyOrgUnit, C=US",
    StoreLocation.CurrentUser, 
    StoreName.TrustedPeople);

// Create a WSHttpBinding and set its security properties. The
// security mode is Message, and the client is authenticated with 
// a certificate.
EndpointAddress ea = new EndpointAddress("http://contoso.com/");
WSHttpBinding b = new WSHttpBinding();
b.Security.Mode = SecurityMode.Message;
b.Security.Message.ClientCredentialType =
    MessageCredentialType.Certificate;

// Create the client with the binding and EndpointAddress.
CalculatorClient cc = new CalculatorClient(b, ea);

// Set the client credential value to a valid certificate.
cc.ClientCredentials.ClientCertificate.SetCertificate(
    StoreLocation.CurrentUser,
    StoreName.TrustedPeople,
    X509FindType.FindBySubjectName,
    "client.com");