Typo I think. It should say to extract the kernel with pacifist from OS X Install ESD/Packages/Essentials.pkg/System/Library/Kernels/Kernel... for Yosemite.
Can't find the following in the latest Yosemite official release (appstore):
Copy BaseSystem.chunklist and BaseSystem.dmg from InstallESD.img to the root of your USB drive.
doesn't exist :S
Kernel location updated. Downloading the GM now to check the other bit, will update again in a few hours.