Why? CD/DVD drivers are becoming less and less common. I've tried installing operating systems from USB drives with varing levels of success. Most of the time the USB drives are just too slow, especially in old PCs, some won't even give a USB devices as a boot option. So many PCs have network boot ROMs built into the box Pendrives can easily be misplaced. Your going to be pluggin a network cable in most cases, why not boot using it too?
Goals Add EFI support Persistant storage WinPE Web interface to manage boot menu/options
Issues Rasbian only comes with syslinux 4.05
References www.geniso.com/raspberry-pi-as-a-pxe-tftp-nfs-proxy-dhcp-server/ elinux.org/R-Pi_PXE_Server nathanpfry.com/how-to-customize-an-ubuntu-installation-disc