How to customize the emscripten:: val?

I want to customize the emscripten::val type as follows:
class myVal : public emscripten::val {
public:
template
explicit myVal(T&& value) : emscripten::val(value) {}

explicit myVal(const char* v) : emscripten::val(v) {}

myVal(myVal&& v) : emscripten::val(v) {}

myVal(const myVal& v) : emscripten::val(v) {}

static myVal object() {
return myVal(emscripten::val::object());
}
};
What rules should I follow to operate?

There are other static class definitions,

static inline myVal module1 = myVal :module_ property("module");

How do I register this class into the system?