Managed C++ doesn't provide those keywords, which are C# features, not .NET
features. AFAIK, it isn't possible to write a C++ function that C# views as
having out parameters, but you can write a C++ function that C# views as
having ref parameters. For example:

// a1.cpp

#using <mscorlib.dll>
using namespace System;

public __gc struct X
{
  int x;

  X()
  :  x(2)
  {
  }

  void f1(int __gc * x)
  {
     ++*x;
  }

  static void f2(X __gc * __gc * p)
  {
     X* q = new X;
     q->x = (*p)->x;
     ++q->x;
     *p = q;
  }
};

// a.cs

using System;

public class MyClass
{
  static void Main()
  {
     X x = new X();
     X x2 = x;
     int i = 0;
     Console.WriteLine("i = {0}", i);
     x.f1(ref i);
     Console.WriteLine("i = {0}", i);
     Console.WriteLine("x RefEquals x2 == {0}",
           Object.ReferenceEquals(x, x2));
     Console.WriteLine("x.x = {0}", x.x);
     Console.WriteLine("x2.x = {0}", x2.x);
     X.f2(ref x);
     Console.WriteLine("x RefEquals x2 == {0}",
           Object.ReferenceEquals(x, x2));
     Console.WriteLine("x.x = {0}", x.x);
     Console.WriteLine("x2.x = {0}", x2.x);
  }
}

C>cl -LD -clr -W3 a1.cpp
C>csc a.cs /r:a1.dll
C>a
i = 0
i = 1
x RefEquals x2 == True
x.x = 2
x2.x = 2
x RefEquals x2 == False
x.x = 3
x2.x = 2