In which way? Do you want to prevent them opening the HTML containing the editor or reject access to the file browser? If you are trying to achieve the first, this is out of the scope of the editor. You have to implement your own code an intercept requests on a special url basis.
I want the normal MediaWiki editor to display and for there to be no access to the FCKeditor, just as happens if users choose to disable in "my preferences" > "Misc".
Re: Disabling by default?
Re: Disabling by default?