From FCKeditor Docs

How to set config settings when instantiating:

$oFCKeditor->Config['varName'] = 'value';

These variables will be available as editorInstance.Config.varName

There are some settings that should be explained before the config options as they can be set only here, not in the config file:

$oFCKeditor->Width = '100%' ;
$oFCKeditor->Height = '200' ;
$oFCKeditor->ToolbarSet = 'Default' ;