Adding paths to view engine without subclassing

gistfile1.cs

var viewEngine = (RazorViewEngine)ViewEngines.Engines.Single(ve => ve is RazorViewEngine);
viewEngine.PartialViewLocationFormats = new List<string>(viewEngine.PartialViewLocationFormats)
{
    "~/Views/Shared/Fields/{0}.cshtml",
    "~/Views/Shared/ReadOnlyModels/{0}.cshtml",
}.ToArray();