We are planning to perform an Rolling Pool Upgrade using the "automatic method" described in the Citrix XenServer ® 6.1.0 Installation Guide (at http://support.citrix.com/servlet/KbServlet/download/32308-102-691301/installation.pdf)
In order to use the "Automatic Mode" (to avoid installing with media at each host), we attempted to set up a local HTTP repository (or mirror) with the contents of the ISO. We chose this method because we have no NFS or FTP services in place, currently.
Because it was handy, I added a virtual directory (named "media") to an existing IIS web instance and enabled Directory Browsing (mostly for troubleshooting). Then I extracted the ISO into a sub-directory (named "xenserver-6.1") and verified the directory listing matched the contents of the ISO.
At this point I thought I was ready and I performed a test install using HTTP as the method and the address ("http://servername/media/xenserver-6/1"). When this test failed, I began researching the required contents of the directory and several other theories.