How to Make a Bootable OS X El Capitan GM / Beta USB Installer Drive
Many Mac users interested in running OS X El Capitan may wish to have a bootable install drive of the new operating system. We’re going to demonstrate how to do this with a USB flash drive, but technically you can create a boot installer out of just about any USB device which has sufficient space. The process of creating the boot installer for OS X 10.11 is easy enough, though users should have some experience and comfort with the command line before attempting to do so.