I found this http://wiki.centos.org/HowTos/InstallFromUSBkey So for centos 7 if did the dd command seemed to work great. I did the install. So now I'd like to "modify" the USB key to add a boot menu option with my customer install options. I mounted /dev/sdb2 and edited the file /mnt/usb/EFI/BOOT/grub.conf added my menu item and rebooted to try to use it. It does not show up in the menu. How do I get the USB to use my new menu? Thanks Jerry