app_inflector.php

class AppInflector extends Inflector {
	function slug($string, $replacement = '_') {
		$map = array(
			'ã' => 'a',
			'õ' => 'o'
		);
		$string = str_replace(array_keys($map), array_values($map), $string);
		return Inflector::slug($string, $replacement);
	}
}