design question with using call_traits and functors

Hello,

I want to make a functor which uses automatically an reference type if 
the provided value isn't a pointer.

Now I have thougth to use the call_traits library.

template<typename Value>
struct Setter
{
	typedef void result_type;

	void operator()(const std::wstring& newVal, Value* pVal)
	{
		*pVal = boost::lexical_cast<typename Value>(newVal);
	}

	void operator()(const std::wstring& newVal, typename 
boost::call_traits<Value>::reference refVal)
	{
		refVal = boost::lexical_cast<typename Value>(newVal);
	}
};

To call the function I have the following statement:

SetValue setter = boost::bind(Setter<short>(),_1,x);

Now the only thing that I don't like very much is that the user has to 
provide the template argument for setter. Is there some possibility to 
solve it that the template argument is automatically deduced?
Important is that I have to possible calls one when the value is 
provided as value -> I need to have a reference parameter and the other 
is when a pointer is provided.

It would be great if someone can give me a hint.

Best regards
Hansjörg