I've updated the post with instructions that should work for both versions:
[ul][li]Type /dopusdata/Buttons/Menus into the location field.[/li]
[li]Copy the downloaded .dop file over the top of ContextMenu.dop[/li]
[li]Restart Opus (if the change isn't immediate).[/li]
[li]If you wish to restore the default menu later, you can do so via Settings -> Customize -> Context Menu.[/li][/ul]