I searched high an low and still cannot find a definite answer.

How do I configure IIS 7.0 or a Web Application in IIS so that ASP.NET Runtime will handle all requests -- including ones to static files like *.js, *.gif, etc?

What I'm trying to do is as follows.

We have kind of SaaSy site, which we can "skin" for every customer. "Skinnig" means developing a custom master page and using a bunch of *.css and other images.

Quite naturally, I'm using VirtualPathProvider, which operates like this:

public override System.Web.Hosting.VirtualFile GetFile(string virtualPath)
{
    if(PhysicalFileExists(virtualPath))
    {
        var virtualFile = base.GetFile(virtualPath);
        return virtualFile;
    }

    if(VirtualFileExists(virtualPath))
    {
        var brandedVirtualPath = GetBrandedVirtualPath(virtualPath);
        var absolutePath = HttpContext.Current.Server.MapPath(brandedVirtualPath);

        Trace.WriteLine(string.Format("Serving '{0}' from '{1}'", 
            brandedVirtualPath, absolutePath), "BrandingAwareVirtualPathProvider");

        var virtualFile = new VirtualFile(brandedVirtualPath, absolutePath);
        return virtualFile;    
    }

    return null;
}

The basic idea is as follows: we have a branding folder inside our webapp, which in turn contains folders for each "brand", with "brand" being equal to host name. That is, requests to http://foo.example.com/ should use static files from branding/foo_example_com, whereas http://bar.example.com/ should use content from branding/bar_example_com.

Now what I want IIS to do is to forward all requests to static files to StaticFileHandler, which would then use this whole "infrastructure" and serve correct files. However, try as I might, I cannot configure IIS to do this.