Using CS3 ,need to access FileReference class add on properties and methods in Flash Player 10

Hi All

My aim is to access the FileReference class Flash Player 10 properties,methods and Events using CS3 instead of CS4.For load() ,save() methods needs runtime version of Flash Player 10.I need to include the flash player 10 in CS3 publish settings Version.Otherwise you can suggest how i can able to access the FileReference class new properties and methods without CS4.