gistfile1.cs

public class ConcreteLoader : ILazyComponentLoader
{
    public IRegistration Load(string key, Type service)
    {
        // to make sure it really is concrete type
        if (!(service.IsClass&&service.IsAbstract==false))
        {
            return null;
        }

        return Component.For(service).Named(key);
    }
}

// and you just register the loader in the container. That's all