Unity 4.0.what? recent versions of 4.x have more granular Class of Service options for admin access (read only, no access, read update, delete). This provides "levels" of access to the admin interface of sorts. Is this the type of thing you're asking about?
It's not a feature you turn on/off - it's in the Class of Service. I believe the granular options weren't added till 4.0(5), however, so you may not see them in 4.0(4) - you can check the admin guides - here's a link to the COS settings in the admin guide for 4.0(5):
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.