Setting up correct dependency injection in Episerver CMS site not based on Alloy.

DependencyResolverInitialization.cs

using System.Web.Mvc;
using EPiServer.Framework;
using EPiServer.Framework.Initialization;
using EPiServer.ServiceLocation;
using EPiServer.Web.Mvc;
using EPiServer.Web.Mvc.Html;

namespace DependencyInjection
{
    [InitializableModule]
    public class DependencyResolverInitialization : IConfigurableModule
    {
        public void ConfigureContainer(ServiceConfigurationContext context)
        {
        }

        public void Initialize(InitializationEngine context)
        {
            DependencyResolver.SetResolver(new ServiceLocatorDependencyResolver(context.Locate.Advanced));
        }

        public void Uninitialize(InitializationEngine context)
        {
        }

        public void Preload(string[] parameters)
        {
        }
    }
}

ServiceLocatorDependencyResolver.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using EPiServer.ServiceLocation;

namespace DependencyInjection
{
    public class ServiceLocatorDependencyResolver : IDependencyResolver
    {
        readonly IServiceLocator _serviceLocator;

        public ServiceLocatorDependencyResolver(IServiceLocator serviceLocator)
        {
            _serviceLocator = serviceLocator;
        }

        public object GetService(Type serviceType)
        {
            if (serviceType.IsInterface || serviceType.IsAbstract)
            {
                return GetInterfaceService(serviceType);
            }
            return GetConcreteService(serviceType);
        }

        private object GetConcreteService(Type serviceType)
        {
            try
            {
                // Can't use TryGetInstance here because it won’t create concrete types
                return _serviceLocator.GetInstance(serviceType);
            }
            catch (ActivationException)
            {
                return null;
            }
        }

        private object GetInterfaceService(Type serviceType)
        {
            object instance;
            return _serviceLocator.TryGetExistingInstance(serviceType, out instance) ? instance : null;
        }

        public IEnumerable<object> GetServices(Type serviceType)
        {
            return _serviceLocator.GetAllInstances(serviceType).Cast<object>();
        }
    }
}

_serviceLocator.GetAllInstances(serviceType) will return IEnumerable. Do you still need to cast to object again?