Recently I wanted to upgrade the firmware of my thinkpad, and located the firmware download page from Lenovo (which annoyingly do not allow access via Tor, forcing me to hand them more personal information that I would like). The download from Lenovo is a bootable ISO image, which is a bit of a problem when all I got available is a USB memory stick. I tried booting the ISO as a USB stick, but this did not work. But genisoimage came to the rescue.
The geteltorito program in the genisoimage binary package is able to convert the bootable ISO image to a bootable USB stick using a simple command line recipe, which I then can write to the most recently inserted USB stick:
geteltorito -o usbstick.img lenovo-firmware.iso sudo dd bs=10M if=usbstick.img of=$(ls -tr /dev/sd?|tail -1)
This USB stick booted the firmware upgrader just fine, and in a few minutes my machine had the latest and greatest BIOS firmware in place.