How to add users in IIS Manager for an ASP.NET 4.0 application?

I have installed an ASP.NET 4.0 Web forms application in IIS 7.5. If I set the application pool to DefaultAppPool (.NET Framework 2.0) I get the icons for Providers, .NET-Roles and .NET-Users displayed on the configuration page for the application in IIS Manager and I can manage users and roles within IIS. (I’m using Forms authentication.)