If you want to mount a WIM-image with ImageX, you can mount it with read-only access or with write-access.
To mount a WIM-image with read-only access, type:
imagex /mount %path_to_wim_folder%\%filename%.wim 1 %path_to_destination_folder%
For example:
imagex /mount C:\wimfiles\win7.wim 1 C:\mounted_images