public class PasswordDigestChannelFactory<TPortTypeClient, TPlugin>

    where TPortTypeClient : ClientBase<TPlugin>, TPlugin, new()

    where TPlugin : class

{

    public PasswordDigestChannelFactory(string endpointConfigurationName)

    {

        _endpointConfigurationName = endpointConfigurationName;

    }

    private readonly string _endpointConfigurationName;

    public TPlugin GetClient()

    {

        var args = new[] {_endpointConfigurationName};

        var portInstance = Activator.CreateInstance(typeof (TPortTypeClient), args) as ClientBase<TPlugin>;

        // replace ClientCredentials with UsernameClientCredentials

        var username = "username";

        var password = "password";

        var credentials = new UsernameClientCredentials(new UsernameInfo(username, password));

        portInstance.ChannelFactory.Endpoint.Behaviors.Remove(typeof (ClientCredentials));

        portInstance.ChannelFactory.Endpoint.Behaviors.Add(credentials);

        return portInstance as TPlugin;

    }

}

//  StructureMap injection

For<PortType>()

    .Use((new PasswordDigestChannelFactory<PortTypeClient, PortType>("endPoint")).GetClient());