Cross posting from evan on another discussion...
Run userrole.php from the scripts directory.
In the 0.9.0 release version, the first user will be marked as the site owner and they can add other administrators and moderators.
I believe it's looking for the PHP extension "tidy."
There is more information available on the php.net documentation site:
Can you check your PHP installation to see if this extension is enabled?
Thanks for your comments, @mattstewart. I'm working on the system administration documentation. I'd love to get your help with it. Would you be able to add notes to this wiki page and let me know what the things were which weren't obvious?