Hi,
you can enter the full path to the file in the location field at the top of the IIS manager. It shoudl look something like:
[servername] > sites > default web site >
click to the right of that text, then add the path (i.e. "admin/redirect403_4.asp"). now when that file is selected, double click the ssl properties icon and uncheck 'require ssl'
Cheers, Mike.