Dism /Mount-WIM /WimFile:c:\winpe_x86\winpe.wim /index:1
/MountDir:c:\winpe_x86\mount
Dism /image:<path_to_image> /Add-Driver
/Driver:c:\winpe_x86\mount\Windows\driver.inf
dism /unmount-wim /Mountdir:c:\winpe_x86\mount /commit
Dism /Mount-WIM /WimFile:c:\winpe_x86\winpe.wim /index:1
/MountDir:c:\winpe_x86\mount
Dism /image:<path_to_image> /Add-Driver
/Driver:c:\winpe_x86\mount\Windows\driver.inf
dism /unmount-wim /Mountdir:c:\winpe_x86\mount /commit