It looks like the "generated.iso" that "cobbler buildiso" creates is somewhat broken.
I had to install syslinux on the USB stick to get it to boot.
Then I had to move isolinux/ --> syslinux/ Then move syslinux/isolinux.cfg --> syslinux/syslinux.cfg Afterwards, I had to make multiple edits to the syslinux.cfg :
" To start with, there are leading blank lines
DEFAULT menu [--> DEFAULT /syslinux/menu.c32] PROMPT 0 MENU TITLE Cobbler | http://cobbler.et.redhat.com TIMEOUT 200 TOTALTIMEOUT 6000 ONTIMEOUT local
LABEL local MENU LABEL (local) MENU DEFAULT KERNEL chain.c32 [ --> KERNEL /syslinux/chain.c32] APPEND hd0 0
LABEL rhel5-x86_64 MENU LABEL rhel5-x86_64 kernel 1.krn [ --> /syslinux/1.krn] append initrd=1.img [ --> initrd=/syslinux/1.img] ks=http://127.0.0.1/cblr/svc/op/ks/profile/rhel5-x86_64 [ --> ks=http://xx.xx.xx.xx./cobbler/ks_mirror/rhel5-64.ks] ksdevice=bootif lang= kssendmac text
MENU END "
BTW, The iso will not even istall from CD without changing the "ks=" line.
cobbler-2.0.3.1-3.el5