Attach Normal Class Method As Event Of A Model

i`ve got normal (not static) class, which method i want to attach to a model and execute somewhere in afterSave() method.

ive got problems attaching it in models __construct() method as it is firing up too many times.

when i try to attach it in config:

		'proceeded' => array(

			'onProceeded' => array(new CEventProceeded(), 'performCascadeProceeding'),


it says:

while the class path is added to import and works.

where and when should i attach it?