Need help with ExtendScript's ExternalObject integration.

I've been working with the SampleLib example (https://github.com/Adobe-CEP/CEP-Resources/blob/master/ExtendScript-Toolkit/Samples/cpp/source/samplelib/SampleLib.cpp) and I think I've got the basics figured out - I can fetch properties and call methods. What I don't understand, and am having a difficult time finding, is any information for handling nested objects.

Here's an example of what I'm trying to work with:

class NestedClass {

TaggedData c;

public:

    TaggedData getC(){return c.data.intval;};

    NestedClass(TaggedData _c){c = _c;};

};

class MyClass {

public:

    TaggedData a;

    TaggedData b;

TaggedData nClass;

    MyClass(TaggedData _a, TaggedData _b){

        a = _a;

        b = _b;

    };

    ~MyClass(){};

    int getSum(){

        return a.data.intval + b.data.intval;

    }

    int getNestedClassValue(){

        return nClass.getC();

    }

};

I can't seem to initialize nClass properly. 

Any help or pointers to where there's a good example would be greatly appreciated.