Q. How do I use DISM to mount and unmount images?
A. DISM provides the ability to mount WIM and VHD files, make changes such as apply drivers or updates and then dismount, saving the changes. Below are three simple DISM commands that first list images in a file, mount the file and then dismounts (discarding changes but could also /commit).
dism /get-imageinfo /imagefile:"c:\temp\install.wim" dism /Mount-Image /ImageFile:"c:\temp\install.wim" /index:3 /MountDir:c:\wimmount dism /unmount-image /mountdir:c:\wimmount /discard