You can also develop your code assemblies in #develop then use DbcClr.exe (comes with the .NET SDK distributions) as a debugger that supports "Atttach to Process.."
Then you point a browser to your app (must be hosted on your local machine of course) to start up the ASP.NET worker process (aspnet_wp.exe) and use DbcClr.exe's "Attach to Process" feature to monitor that process. Open a file (cs, vb, even aspx, etc), set a breakpoint, then trigger that code functionality through your browser and DbgClr will stop.
I have used this setup extensively as i prefer #d to Visual Studio and code the HTML/CSS part of ASP.NET by hand.