gistfile1.php

<?php
	function _findAccessible($state, $query, $results = array()) {
		if ($state == 'before') {			
			if (isset($query[0]) && is_numeric($query[0])) {
				$query['conditions'][$this->alias . '.id'] = $query[0];
			}
			$query['fields'] = $this->primaryKey;
			$query['recursive'] = -1;
			return $query;
		} elseif ($state == 'after') {
			$results = Set::extract('/' . $this->alias . '/id', $results);
			foreach ($results as $id) {
				$results = array_merge($results, $this->find('accessible', array(
					'conditions' => array($this->alias . '.supervisor_id' => $id)
				)));
			}		
			return array_unique($results);
		}
	}