!!! Execute all as root !!!
VERSION=”Mavericks”
or
VERSION=”Yosemite”

# Mount the installer image

hdiutil attach /Applications/Install\ OS\ X\ ${VERSION}.app/Contents/SharedSupport/InstallESD.dmg -noverify -nobrowse -mountpoint /Volumes/install_app

# Convert the boot image to a sparse bundle

hdiutil convert /Volumes/install_app/BaseSystem.dmg -format UDSP -o /tmp/${VERSION}

# Increase the sparse bundle capacity to accommodate the packages

hdiutil resize -size 8g /tmp/${VERSION}.sparseimage

# Mount the sparse bundle for package addition

hdiutil attach /tmp/${VERSION}.sparseimage -noverify -nobrowse -mountpoint /Volumes/install_build

# Remove Package link and replace with actual files

rm /Volumes/install_build/System/Installation/Packages
cp -rp /Volumes/install_app/Packages /Volumes/install_build/System/Installation/

# Unmount the installer image

hdiutil detach /Volumes/install_app

# Unmount the sparse bundle

hdiutil detach /Volumes/install_build

# Resize the partition in the sparse bundle to remove any free space

hdiutil resize -size `hdiutil resize -limits /tmp/${VERSION}.sparseimage | tail -n 1 | awk ‘{ print $1 }’`b /tmp/${VERSION}.sparseimage

# Convert the sparse bundle to ISO/CD master

hdiutil convert /tmp/${VERSION}.sparseimage -format UDTO -o /tmp/${VERSION}

# Remove the sparse bundle

rm /tmp/${VERSION}.sparseimage

# Rename the ISO and move it to the desktop

mv /tmp/${VERSION}.cdr ~/Desktop/${VERSION}.iso