The reference for liveUSB (be careful, there are several outdated tutorials for liveUSB on the website).
As root, from /mnt/cdrom:
# create as many partitions as you want with fdisk or parted or gparted ; we will install sysrescuecd on the first one. mount -o loop,exec,ro systemrescuecd-x86-x.y.z.iso /mnt/cdrom usb_inst/install-mbr /dev/sdb --force usb_inst/parted -s /dev/sdb set 1 boot on ./usb_inst.sh format /dev/sdb1 ./usb_inst.sh copyfiles /dev/sdb1 ./usb_inst.sh syslinux /dev/sdb1