Live skeleton DVD to contain backed up data

Has anyone done this or is there an easier way of doing it...

I use kdar to backup my linux install onto a DVD. To restore, I first boot with live Knoppix, but then I have to swap with my data DVD. And there's the rub. I don't know how to unmount the Konppix CD so that I can mount the data DVD! Is there a way to do that? If not, I'd like a remastered Knoppix DVD skeleton with only kdar, its dependencies and maybe some other tools. I will then use this skeleton as a template and populate it with my backups.

Thanks for your advice!