如何序列化未设计为序列化的类？

I need to save some classes and data structures to a file. My first reflex was to use XML or Binary serialization but this is turning into a nightmare. I have a set of classes that were not meant to be serialize (private setters, no parameterless constructors, no Serialization attribute, dictionaries, etc.). Considering that I cannot change those classes, what should I do? Is there any workaround this and still use serialization?I need to save some classes and data structures