This is a "dumb" extension (It just passes what is assumed valid Jade syntax and does nothing else). If your files are not valid Jade syntax it will throw an error.
The syntax is similar to Haml,
Just extract into your extensions folder
//Add to Components 'components'=>array( ... 'viewRenderer'=>array( 'class'=>'ext.jade.CJade', ), ....
Tested with Yii 1.1.13
Syntax Definition: Jade Info