Open up Open IV and ensure "edit mode" is turned on - 


Navigate to mods / update / x64 / dlcpacks
Drag and drop "21doddurango" folder into dlcpacks
Navigate to mods / update / update.rpf / common / data / dlclist.xml
Copy and paste in the following line under your last line:
<Item>dlcpacks:/21doddurango/</Item>
Save and close


ELS XML goes into your els folder