Upgrading Xerces to last version in Idea 4.0.x and 4.5.x

Did anyone try to upgrade xerces version of idea 4.0.x and 4.5.x to the last one ?

My plugin need xerces 2.7.x and because of classloaders issues i can't make it run under 4.0x and 4.5.x

When i upgrade the jars i've got an error :
java.lang.NoSuchMethodError: org.w3c.dom.Node.setUserData(Ljava/lang/String;Ljava/lang/Object;Lorg/w3c/dom/UserDataHandler;)Ljava/lang/Object;

It seems like wrong version of Node is taken somewhere !?