Custom Config

No matter what I try, I cannot seem to get a customer config loaded.

The directory structure is;

webroot/blog/ckeditor
and
webroot/blog/custom

in config.js I've put config.customConfig = '/blog/custom/ckeditor_config.js';

in the ckeditor_config.js I have
CKEDITOR.editorConfig = function( config )
{
// Define changes to default configuration here. For example:
config.baseHref = 'http://www.bedaleswines.com/blog/';
config.contentsCss = '/blog/themes/bedales/inc-stylesheet.css';
config.height = '500px';
config.toolbar =
[
['Source','-','Preview'],
['Cut','Copy','Paste','PasteText','PasteFromWord','-','Print', 'SpellChecker'],
['Undo','Redo','-','Find','Replace','-','SelectAll','RemoveFormat'],
['Form', 'Checkbox', 'Radio', 'TextField', 'Textarea', 'Select', 'Button', 'ImageButton', 'HiddenField'],
['Link','Unlink','Anchor'],
['Image','Flash','Table','HorizontalRule','Smiley','SpecialChar','PageBreak'],
'/',
['Styles','Format','Font','FontSize'],
['TextColor','BGColor'],
['Maximize', 'ShowBlocks','-','About']
];
config.filebrowserBrowseUrl: "/blog/kfm/index.php";

// config.uiColor = '#AADC6E';
};


I can't find anywhere where is says what the relative paths should be

Regards
Pete