I have this code in my cakephp 2:
$root = rtrim($_SERVER['DOCUMENT_ROOT'],'/'); // don't touch this configuration
$root = $root."/cakephp/app/webroot";
$base_url="http://localhost/cakephp"; //url base of site if you want only relative url leave empty
$upload_dir = '/tinymce/source/'; // path from base_url to upload base dir
$current_path = '../../../../source/'; // relative path from filemanager folder to upload files folder
I have followed this structure:
// root(cakephp/app/webroot)
// |- tinymce
// | |- source <- upload folder
// | |- js
// | | |- tinymce
// | | | |- plugins
// | | | |- |- filemanager
// | | | |- |- |- thumbs <- folder of thumbs [must have the write permission]
Hope that this helps to other user.