Various mojoportal features assign a specific toolbar. For users in Admins role the Full toolbar is usually used for other users Full toolbar is used in Html Content feature, Forums toolbar is used in the forums, BloggComment toolbar is used in the blog etc.
These toolbars and their contents are defined in /ClientScript/mojofckconfig.js
FCKeditor is told to use this file by a setting in Web.config so you could use a different file. However to use it in mojoportal you must use the toolbar names I have defined though you could change their contents.
<add key="FCKeditor:CustomConfigPath" value="~/ClientScript/mojofckconfig.js" />
Hope it helps,