We needed to limit almost all FCKeditor font, color and other formatting functionality on a portal. I was really pleased to learn that FCKeditor has a function to choose which toolbars display with the Rich Text editor. I was able to disable all the toolbars and get exactly the minimal FCKeditor functionality our portal required!
=== DNN 4.5.3/FCK 2.4.1 ===
Logged in as Admin; go to an instance of FCKeditor, for example, inside User Manager (Users > [edit a user] > Manage Profile)
Browse down to the default 'Biography' profile property, and click Show custom editor options under FCKeditor window.
Settings Type: Instance, Module, Portal (I selected Portal, but maybe you want more specific FCKeditor instance control)
Editor Toolbar View Options
Click Edit (current toolbar permissons), click Disabled, then click Edit again (update toolbar)
Do this for all available toolbars.
Apply Custom Settings To: Instance, Module, Portal (I selected Portal)
Click Apply
This gave us a stripped down FCKeditor in Rich Text mode - almost like a Basic Text Editor - and nothing more.
Great functionality by design!
Instead of totally disabling a toolbar, set the View Roles so that only selected Roles see certain FCKeditor toolbars.