A colleague of mine Paul Taylor (http://paul-taylor.co.uk/blog/) recently figured out how to do this.
Here's an example that will spin up the Visual studio cassini web host for your project, assuming you place this batch file in the folder the web project sits in.
@echo off
set currentPath=%~dp0
if "%currentPath:~-1%"=="\" SET currentPath=%currentPath:~0,-1%
start WebDev.WebServer.EXE /port:62036 /path:"%currentPath%" /vpath:"/"
start iexplore.exe http://localhost:62036/default.aspx