Of course you can add drivers!
You will need to do the following
First mount the image by typing the following in cmd;
dism /mount-wim /wimfile:w:\myimage.wim /index:1 /mountdir:c:\mymountedimages
Second, type dism /image:c:\mountedimages /add-driver:c:\newdrivers\mydriver.inf
Third, commit the image by typing dism /commit-wim /mountdir:c:\mymountedimages
Finally unmount your image with dism /unmount-wim c:\mymountedimages
myimage.wim needs to be the name of your image file
c:\mymountedimages needs to be a directory where you can mount your images to for editing
c:\newdrivers\mydriver.inf needs to be the full location of your new driver inf
Good luck!
