mount /dev/sdX /media/usb
mount windows.iso /media/windows
cp -rv /media/windows/* /media/usb/
--boot-directory
is the boot
directory inside the iso.
sudo grub-install --target=i386-pc --boot-directory=/usbflash/boot/ /dev/sdX
echo "If you see this, you have successfully booted from USB :)"
insmod ntfs
insmod search_fs_uuid
search --no-floppy --fs-uuid <UUID_from_step_2> --set root
ntldr /bootmgr
boot