Create the following folders on the root of the C drive:
C:\Mount\BootWim

Open a CMD prompt as Administrator

Use the following DISM commands to mount the boot.wim:
DISM /Mount-Wim /WimFile:"\\az-dwm-web01\OSD\AutoUnattend\USB_Stick_Creator\Boot_WIMs\boot_en-GB.wim" /Index:2 /MountDir:C:\Mount\BootWIM

Use the following DISM command to add the driver:
DISM /Image:C:\Mount\BootWIM /Add-Driver /Driver:"\\az-dwm-web01\OSD\AutoUnattend\USB_Stick_Creator\Drivers" /recurse

Use the following DISM command to unmount the boot.wim:
DISM /Unmount-Wim /MountDir:C:\Mount\BootWIM /Commit