Change windows 7 setup default keyboard without Autounattend file

1. Mount your boot.wim with imagex using the /mountrw option or DISM
   ex: imagex /mountrw c:\winpe\iso\sources\boot.wim 1 c:\winpe\mount
   or: DISM /Mount-Wim /Wimfile:h:\AIO\DVD\sources\boot.wim /index:2 /MountDir:H:\AIO\mnt
2. Open regedit, highlight HKEY_LOCAL_MACHINE, go to the File Menu and
   select Load Hive…
3. Browse to {boot.wim mount}\windows\system32\config and select the file
   DEFAULT. Name the hive WINPE_DEFAULT when prompted.
4. Open HKLM\WINPE_DEFAULT\Keyboard Layout\Preload. Change the value 1 from
   00000409 to 00001009.
5. With WINPE_DEFAULT highlighted in regedit, from the File menu select
   Unload Hive… and click Yes if prompted to confirm.
6. Unmount boot.wim with ImageX, making sure to use the /commit option.
   ex: imagex /unmount /commit c:\winpe\mount
7. Replace your DVD’s /sources/boot.wim with the new one

Source: http://www.techtalkz.com/windows-deployment/196087-adding-fr-ca-language-pack-winpe.html