Cocos2d 2.0 - 将精灵集中在一个图层上

I have a CClayer class and when this class inits it creates a CCSprite that should be centered, so later, when I rotate an object created with that CCLayer class, it rotates around its center. I mean, if the sprite on that class is an image 200 pixels wide and 300 pixels height, I want the CCLayer pivot to be at 100,150.I have a CClayer class and when this class init