You can render your viewmodel in MVC, http://jondjones.com/learn-episerver-cms/episerver-developers-guide/episerver-customizing-episervers-ui/how-to-manually-render-a-episerver-page-or-block-using-net

public static class RenderControllerManually
    {
        public static string Render(int pageId, IEpiserverDependencies epiServerDependencies)
        {
            var viewModel = CreatePageTypesViewModel(pageId, epiServerDependencies);
            
            var viewDataDictionary = new ViewDataDictionary(viewModel);

            var controller = new ContentPageController();
            var controllerName = GetControllerName(controller);

            var routeData = new RouteData();
            routeData.Values.Add("Action", "Index");
            routeData.Values.Add("controller", controllerName);

            var siteUrl = EPiServer.Configuration.Settings.Instance.SiteUrl.ToString();

            var httpContext = new HttpContext(
                    new HttpRequest(string.Empty, siteUrl, string.Empty),
                    new HttpResponse(TextWriter.Null));

            var controllerContext = new ControllerContext
            {
                RouteData = routeData,
                Controller = controller,
                HttpContext = new HttpContextWrapper(httpContext)
            };

            var viewResult = ViewEngines.Engines.FindPartialView(controllerContext,
                                                     "~/Views/Pages/ContentPage/index.cshtml");

            using (var stringWriter = new StringWriter())
            {
                var viewContext = new ViewContext(controllerContext,
                                                  viewResult.View,
                                                  viewDataDictionary,
                                                  new TempDataDictionary(),
                                                  stringWriter);

                viewResult.View.Render(viewContext, stringWriter);

                return stringWriter.ToString();
            }
        }

        private static string GetControllerName(ContentPageController controller)
        {
            var controllerName = controller.GetType().Name;

            var index = controllerName.IndexOf("Controller");
            return index < 0
                ? controllerName
                : controllerName.Remove(index, "Controller".Length);
        }

        private static ContentPageViewModel CreatePageTypesViewModel(int pageId, IEpiserverDependencies epiServerDependencies)
        {
            var repository = ServiceLocator.Current.GetInstance<IContentRepository>();
            var contentReference = new ContentReference(pageId);

            var contentPage = repository.Get<ContentPage>(contentReference);


            return new ContentPageViewModel(contentPage, epiServerDependencies);
        }

I missed the point from your question "This is for a web form based project", Can you please let us know, which cms version you are using

Thanks Khurram for the input, The CMS version is 9.