The best method possible really depends on how you are setup. If you contact red hat they are just going to try and sell you satellite.
--What we do for our offline environment is we have created a mirror using reposync. It comes in yum-utils package.
Do you have at least one computer connected to rhn outside of disconnected computers?
In a sense you'll want to create an online repository/mirror to clone into offline environment. This is really easy if you are using vm, which is what we use.
So first -- Install yum-utils package
Next -- Setup a directory to download files
Then -- Download packages using reposync
For example we use command: (grabs all packages availble through rhn)
Code:
reposync -l -p /var/my/ftp/repo/path
NOTE: It takes a while for all of the packages to download.
Then either take img here OR create repository first then take img
Do you know how to create repository?