This live CD is customized by roughly following the guidelines at:
https://
  help.ubuntu.com/community/LiveCDCustomization
  help.ubuntu.com/community/LiveCDCustomizationFromScratch
  help.ubuntu.com/community/MakeALiveCD/DVD/BootableFlashFromHarddiskInstall
plus a lot of other info, like ubiquity and casper source code, and
additions for making the resulting iso EFI bootable.

Run things in generally this order:

extractiso.sh
  extract the original iso

customize.sh
  apply customizations

enter.sh
  chroot into the install (for optional manual customization)

buildiso.sh
  build the new iso

run.sh -c
  boot the iso in qemu with a blank hdd, to test the install

run.sh -d
  boot the installed hdd in qemu

cleanup.sh
  remove everything but the isos