Describe the way to set up GitLab Pages with Access Control on a separate server

I have found and documented the method to run GitLab Pages in a separate server on omnibus instance, however I was not not able to make it work with Access Control enabled.

If this is at all possible, could you please describe it in the docs? If not, please consider it as a feature proposal.

ZD ticket (internal only): https://gitlab.zendesk.com/agent/tickets/110436