how do I add the ability for logged-in users to contact the administrator?
At the moment the only way for people to contact the administrator is from the log-in form.
Unfortunately, the option for "please contact your JIRA administrators." is only avaiiable on the log-in form as you describe. One alternative would be to post a banner message (admin panel ->issues -> User Interface -> Announcement Banner) though this is most commonly used for when setting up an account or making changes.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.