Not sure with what your trying to add to a folder, I normally install the base OS, and use slmgr -ilc to import the cert (from any folder) then slmgr -ipk to set the product key. Windows then becomes activated.
Major Update to Problem Resolution: First off Huge Thanks to Tito for his willingness to look at my situation from his perspective, this was paramount to resolving the problem. I post my personal letter to him for the remainder of this post.
Those ISO modifying tools are terrible, much safer to recreate the ISO from files using command line and CDIMAGE Things can get quite pear shaped when there are multiple file systems in the ISO, as Juliet, ISO9660 and UDF.