To extract/edit .WIM files a small command line tool is needed, namely ImageX.
It works as following: A .WIM file needs to be mounted to a existing
directory, which means the contents of the file is kind of copied to that
directory. Here it can be read and/or edited. Finally, when unmounting the
directory all is back to normal (and if the /COMMIT switch is used the
changes will be written back to the .WIM file).
The utility ImageX.exe can be downloaded by clicking the following
Hope this helps