Matt/Adrian,
I don't think the tools/scripts on the Admin wiki are required for this situation. You can select a custom role for new enterprise login users (just as long as the custom role doesn't have any administrative privileges, which it sounds like in your case it doesn't) in the organization settings.
My Organization > Edit Settings > Security > Enterprise Logins > Edit Identity Provider >
Hope this help!
Owen
Owen Evans
Lead Product Engineer | StoryMaps