Problem: How do I inject drivers into a .wim file?
Solution:
First you need to mount the image file, this is achieved by running the following:
dism /mount-wim /wimfile:<YourImage File.wim> /Index:1 /mountdir:"C:\temp\Mount"
You then need to specify a driver directory to which you have all the .inf files prepared and run the below:
dism /image:"C:\temp\Mount" /add-driver /driver:"C:\temp\Drivers" /recurse /forceunsigned
All you need to do now is commit the changes to the original .wim file:
dism /unmount-wim /mountdir:"C:\temp\Mount" /commit
Then clean-up the image:
DISM /Cleanup-Wim