Code:

Option Explicit On
Option Strict On
Option Infer Off

Imports System.Runtime.InteropServices

Friend Class EntryPoint

    Class NativeMethods
        Private Const KERNEL32_DLL As String = "Kernel32.dll"
        <DllImport(KERNEL32_DLL)> _
        Friend Shared Function LoadLibrary(ByVal szFileName As String) As IntPtr
        End Function
        <DllImport(KERNEL32_DLL)> _
        Friend Shared Function GetProcAddress(ByVal hLibrary As IntPtr, ByVal szProcName As String) As IntPtr
        End Function
        <DllImport(KERNEL32_DLL)> _
        Friend Shared Function FreeLibrary(ByVal hLibrary As IntPtr) As Integer
        End Function
    End Class

    <UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet:=CharSet.Unicode)> _
    Delegate Function MessageBoxProto(ByVal hWndParent As IntPtr, ByVal szText As String, ByVal szTitle As String, ByVal ulFlags As UInt32) As Integer

    Friend Shared Sub Main()

        Dim hUser32 As IntPtr = NativeMethods.LoadLibrary("User32.dll")
        Dim pMethod As IntPtr = NativeMethods.GetProcAddress(hUser32, "MessageBoxW")
        Dim MessageBox As MessageBoxProto = DirectCast(System.Runtime.InteropServices.Marshal.GetDelegateForFunctionPointer(pMethod, GetType(MessageBoxProto)), MessageBoxProto)
        MessageBox.Invoke(IntPtr.Zero, "hello there", "cool!", Convert.ToUInt32(MsgBoxStyle.Information Or MsgBoxStyle.SystemModal))
        NativeMethods.FreeLibrary(hUser32)

    End Sub

End Class