That last command will show you the contents of the ISO file . . . you can read it, copy files from it, but ( of course ) not write to the ISO.
But what you can do is copy the files to a special directory ( or partition ) and do an install from the HD. In the case of the Fedora example above you would put the files of the 4 ISO's in a directory. Then download the "boot.iso" from the ftp mirror ( For Fedora Core 4:
ftp://ftp.nluug.nl/pub/os/Linux/distr/fedora/core/4/i386/os/images/boot.iso ).
1). Boot from the boot-CD
2). It will give you a dialog where you want to install from: choose "hard disk"
3). The next dialog will ask you from which HD ( if you have 2 )
4). After that a dialog will ask you on what partition the files are located
5). And the next dialog asks "Directory or ISO image _________" type the path to the directory you copied the files to and press OK
After that, the program will load into memory and proceed to go on as a normal install. This way you only have to burn 1 CD instead of 4.

Bruno
NOTE: The Mandriva 2005 has a new feature in the boot.iso that can install directly from ISO files stored on the HD without having to "loop" them first.
-- Jun 7 2005 ( Revised Dec 15 2005 ) --