Backing up a clone onto an iPod with Firewire and booting from it...

Hello,
In an earlier thread I was inquiring as to how I would go about making a clone of my computer to backup my files. I unserstand that the best thing to do is use an external firewire hard drive, however, an earlier poster told me that you could do it with the older iPods that support firewire.

I'm new to Macs so I'm kind of clueless as to what I should do when Backing-up my stuff/cloning it. And I'm even more clueless as to how I would boot from my iPod...