So, after looking around for an answer today I finally found out where the Debian install CD stores its cd/usb boot menu configuration files. While I have already had a great deal of experience editing grub.conf files by hand, this methodology simply doesn’t work on an “El Torito” Joliet CDROM image. So Debian set-up their boot image (as part of the initial ram disk) inside of the /ISO/isolinux/ directory where ISO is the uncompressed version of the boot image. Specifically you can configure things like:
- The boot option timeout in /isolinux/isolinux.cfg
- The background splash image in /isolinux./splash.png (640×480 on the default menu set-up)
- Which sub-menu’s, options, boot methods, and GUI installs are available via the /isolinux/menu.cfg
Honestly, I may be the only person on the planet trying to figure this stuff out; but here it is for future reference or for anyone who wants to make their very own custom Debian install CD .