Now I know this will work for BlueHost backups (as of 12/30/2013), but not sure about HostGator or others. When you download the full backup the structure should have the homedir in the root of the tar file, as well as a bunch of other directories such as dnszones, userdata, userconfig, etc. As long as you see those in that root directory of the backup this method should work for you.
Assuming you’re on a linux computer (or the backup has been uploaded to a linux server), you will need to create a new directory, extract the backup file to the new directory, then recreate the backup tar file with a new directory structure.
So assuming our backup file is backup-12.30.2013.tar, first create a new directory to extract to:
Next change to the directory we created and extract the backup file contents
Once this is complete we’re going to use the “cpmove-theuser.tar” naming structure for our file, so let’s go back to the /home2 directory and change the name of our backuptmp directory. Make sure you replace “theuser” with the username this backup was created for!
Now we just need to create a tar from that directory, and you should be able to restore it through WHM…
As you can see, all we had to do was move the entire backup folder structure into a “cpmove-username” directory inside the backup. My assumption is cPanel looks for this directory in the root of the compressed backup, and if it doesn’t exist it will error out and not restore. Hopefully this helps someone else out as I could not find anything about this online and had to test and figure it out myself … good luck!
If you have problems through WHM, you can always try to restore with cPanel through SSH using this command:
taken from: http://smyl.es/how-to-restore-a-bluehost-backup-on-another-cpanel-server-convert-to-default-backuprestore-format/