There aren't enough good samples in C++/CLI.
Any C# to C++/CLI converter should work for this (you can get a demo edition
of Instant C++ at our site - it converts C# to C++/CLI).

I found enough text in this online book to get me started, and I think I
can deduce the rest from the MSDN docs.

http://books.google.com/books?id=_DZpE7tzjKcC

http://msdn.microsoft.com/en-us/library/system.collections.ienumerable.aspx

something like this:

template <typename result, typename iterator>
ref class IteratorWrapper : public IEnumerable<result>
{
   iterator m_begin, m_end, m_current;

public:
   IteratorWrapper(iterator begin, iterator end)
       : m_begin(begin), m_end(end), m_current(begin)
   {}

   bool MoveNext( void ) override { return m_end != ++m_current; }
   property result Value {
       result get() { return *m_current; }
   }
};

Write a template helper function or two to get argument deduction:

template<typename T>
IEnumerable<T>^ WrapIterator(T* begin, T* end)
{
   return gcnew IteratorWrapper<T, T*>(begin, end);
}

template<typename T>
value struct WrapCollection
{
   template<typename T2>
   IEnumerable<T>^ WrapIterator(T2* begin, T2* end)
   {
       return gcnew IteratorWrapper<T, T2*>(begin, end);
   }
};

Now you can enumerate an array:
T[] a = new T(N);
IEnumerable<T>^ e = WrapIterator(a, a+N);

or a vector:
std::vector<T> v;
IEnumerable<T>^ e = WrapCollection<T>::WrapIterator(v.begin(), v.end());

and so on.