I found the easiest way was to extract the files from the exe to a folder and integrate them along with the drivers during nLite config. It extracts a couple of mshda*.inf files (and prob others too), and seems to work a treat.
I just saved the registry settings for this folder and added it to the regtweaks file - [HKEY_CURRENT_USER\Control Panel\International] - once it was setup how I wanted it.