From LedHed's Wiki
Overview
DVDs are old and slow, so you want to install Windows from a bootable USB stick!
Down -N- Dirty
Diskpart
diskpart.exe list disk select disk X (Where X is the number of the USB stick) clean create primary partition select partition 1 format fs=ntfs quick active
Copy
Copy all of the data from the ISO to the root of the USB stick (D:\ in this example).
You can mount the ISO or use 7zip to extract it to D:
Setup the Boot Sector
Copy d:\boot to your C drive and run:
C:\temp\boot\bootsect /NT60 d: /force /mbr
DONE!