The CDROM image was a firmware upgrade image from Dell (based on Linux). Mounting the image with iDRAC, it worked nicely. As one of the Servers had a dying iDRAC (Dell R320), I needed an USB stick.

I created a bootable USB stick using an Ubuntu 8.10 live CD and the (manual) instructions shown at this guide. This worked great. However, what I'd really like to do is create a multi-booting version ...

If you have the ISO image already just use the "Disk Image" fields to point it at the one you want, and you're ready to go. UNetbootin will identify whatever likely candidate (s) it can find for the ...