Host multiple sites in single ASP.NET Development Server

I am working in an environment in which the developers will not be
able to run IIS on their machines. As a solution, I have turned to
using the ASP.NET Development Server (filesystem IIS) but my system
architecture is causing a problem.

First, we have a global theme so that all of our applications share
the same theme. This theme is hosted in IIS under “/aspnet_client/
system_web/2_0_50727/Themes/Project_Theme”.
(filesystem = C:\Inetpub\wwwroot\aspnet_client\system_web
\2_0_50727\Themes\ Project _Theme)

Second, we have an Authentication website that handles validating
users. In order to login a user is redirected to the Authentication
site, using this Web.config entry:
<authentication mode="Forms">
<forms loginUrl="/ Authentication /NewLogin.aspx?
applicationName=NewApp"
name=".ASPXAUTH" protection="All" path="/" timeout="30"
enableCrossAppRedirects="true">
</forms>
</authentication>

I cannot find a way to host the authentication site and the theme
folder in the ASP.NET Development Server while running my Web
Application. As a result, I have to remove my reference to the global
them and disable security while developing.

Can anyone suggest a solution?

Thanks,
Don