SESSION using Yii and normal site (same server)

Hi,

I still have a question regarding to the session. I currently doing a project is already exits. The client would like to add the Yii framework for the coming module in the same portal, so the existing function and module in the portal was remain. Yii is like a sub project in the same domain. Now the problem is i unable to share the SESSION, when login from Yii the session in Yii cannot use in the original portal. The original portal is without fraework. Is there anyway can convert Yii::app()->session[‘localization_popup’] to $_SESSION[‘localization_popup’], or Yii got another type of SESSION define method?