Chrispcritters - 6:32 pm on Jul 18, 2013 (gmt 0)
I manage a few classic ASP sites and we check for HTTP/HTTPS usage and requirement in a common include file that gets processed before most other things.
Prior to the include file a variable RequireSSL is set to either TRUE or FALSE. In the common include if the request is coming in HTTPS and the RequireSSL is FALSE then we redirect to the HTTP page and vice versa.
In my case the HTTPS pages (all within a folder) are blocked via robots.txt and meta robots as well.