1. show hidden files, open terminal : defaults write com.apple.finder AppleShowAllFiles 1 && killall Finder
2. right click on Install OS X xxx, choose "Show Package Contents".
3. Open Contents / Shared Support
3. You'll see a Packages folder. Open terminal, enter: open "/Volumes/OS X Install ESD/BaseSystem.dmg or use finder open/mount InstallESD.dmg (double click it) and BaseSystem.dmg
4. Using Disk Utility, restore OS X Base System to your USB Stick.
5. On the USB Stick, in System/Installation delete the link named Packages
6. Copy Packages from OS X Install ESD to the System/Installation folder on the USB Stick
7. Unhide files from the OS X Install ESD dmg to copy BaseSystem.dmg and Basesystem.chunklist (they are both hidden) and copy them onto the USB stick
8. Unmount USB stick. You now have a full bootable USB stick with the OS.
