MyApplication.cs

using Umbraco.Core;
using Umbraco.Core.Services;
using Umbraco.Web.Mvc;
using Umbraco.Web.Routing;

namespace Our.Umbraco
{
	public class MyApplication : ApplicationEventHandler
	{
		protected override void ApplicationStarting(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
		{
			ContentFinderResolver.Current.InsertTypeBefore<ContentFinderByNotFoundHandlers, ContentFinderForWhatever>();
			base.ApplicationStarting(umbracoApplication, applicationContext);
		}
	}

	// the example here is to have a 'virtual url'.
	// this is required on a specific DocType, after @level=3
	public class ContentFinderForWhatever : IContentFinder
	{
		public bool TryFindContent(PublishedContentRequest contentRequest)
		{
			if (contentRequest != null)
			{
				var path = contentRequest.Uri.GetAbsolutePathDecoded();
				var parts = path.Split(new[] { '/' }, System.StringSplitOptions.RemoveEmptyEntries);
				if (parts.Length > 2)
				{
					var level3 = string.Concat('/', string.Join("/", parts.Take(3)), '/');
					var node = contentRequest.RoutingContext.UmbracoContext.ContentCache.GetByRoute(level3);

					if (node.DocumentTypeAlias == "Whatever")
						contentRequest.PublishedContent = node;
				}
			}

			return contentRequest.PublishedContent != null;
		}
	}
}