Pointers as arguments of Win32 API in VB.NET?? (Adjust screen brightness in VB.NET)

Question

I need to write something like Adjust screen brightness using C# in VB.NET but there is a pointer parameter in SetDeviceGammaRamp(Int32 hdc, void* ramp). In VB6 there is VarPtr() to get around but it is no longer supported. Every code converter does not work with pointers in VB.NET and C-style pointer in Visual Basic .NET states that there is no such thing as pointers in VB.NET so I wonder if there is a way to get around. Also, how should I declare the function?

BTW adjusting screen brightness is solved in C#, Mac OS X, J2ME, Python and even Android.

C# code:

using System;
using System.Text;
using System.Drawing;
using System.Runtime.InteropServices;

namespace Brightness
{

    /// <summary>
    /// Class for manipulating the brightness of the screen
    /// </summary>
    public static class Brightness
    {
        [DllImport("gdi32.dll")]
        private unsafe static extern bool SetDeviceGammaRamp(Int32 hdc, void* ramp);

        private static bool initialized = false;
        private static Int32 hdc;


        private static void InitializeClass()
        {
            if (initialized)
                return;

            //Get the hardware device context of the screen, we can do
            //this by getting the graphics object of null (IntPtr.Zero)
            //then getting the HDC and converting that to an Int32.
            hdc = Graphics.FromHwnd(IntPtr.Zero).GetHdc().ToInt32();

            initialized = true;
        }

        public static unsafe bool SetBrightness(short brightness)
        {
            InitializeClass();

            if (brightness > 255)
                brightness = 255;

            if (brightness < 0)
                brightness = 0;

            short* gArray = stackalloc short[3 * 256];
            short* idx = gArray;

            for (int j = 0; j < 3; j++)
            {
                for (int i = 0; i < 256; i++)
                {
                    int arrayVal = i * (brightness + 128);

                    if (arrayVal > 65535)
                        arrayVal = 65535;

                    *idx = (short)arrayVal;
                    idx++;
                }
            }

            //For some reason, this always returns false?
            bool retVal = SetDeviceGammaRamp(hdc, gArray);

            //Memory allocated through stackalloc is automatically free'd
            //by the CLR.

            return retVal;

        }
    }
}

Why code converters don't work with pointers in VB.NET (There is no class called Pointer(Of T)):

<DllImport("gdi32.dll")> _
Private Shared Function SetDeviceGammaRamp(hdc As Int32, ramp As Pointer(Of System.Void)) As Boolean
End Function

Dim gArray As Pointer(Of Short) = stackalloc
Dim idx As Pointer(Of Short) = gArray

Don't think this is needed as hdc = Graphics.FromHwnd(IntPtr.Zero).GetHdc().ToInt32() does it.

<DllImport("gdi32.dll")> _
Private Shared Function GetDeviceGammaRamp(hdc As IntPtr, lpRamp As IntPtr) As Boolean
End Function