I remember when MS was developing Cassini - I believe they rolled it into VS 05/08, so I think this is a Cassini web server question.
I am using Windows XP with Vi
You can use a Port Forwarding Utility to listen in on a port, say 5000, and then relay all that traffic to Visual Studio's port.
The solution is described in the article, Accessing the Visual Studio ASP.NET Development Server from iPhone.
I have written a blog post based on the above article which summarizes it, Accessing Visual Studio Web Server remotely.