Just a simple trick to import ISO files to the repository using Oracle VM Manager (OVMM). The import function supports imports through protocols http, https and ftp. If you want to do this in the supported way you can use a simple web server to serve the ISO files for you.
Python comes with a simple http server built in. If you have python installed (which is the case on both the OVM server and the OVMM host) you can start it with:
python -m SimpleHTTPServer
In this case I copied the ISO file to OVM server (dom0) and started the http server there, and the URL for the import becomes as shown in the capture below (or use the IP address of the server where the ISO file is located and remember to use port 8000):
The name of the imported ISO is the same as the file name, rename to a say Oracle Linux 6 U5 and put in the origin of the file in description.