So if you are like me and you occasionally get put in a position where you are rebuilding an existing classic asp program the be big question is 'How do I debug it??'
There are plenty of useful links and most of them will get you about 80% of the way there. I came across a slick trick that works instantly.
Set IIS to run in IIS 5.0 isolation mode and then to debug attach to the dllhost.ext process. And then you are set!