You must use ShellExecute. ShellExecute is the only API that knows how to launch Consent.exe in order to elevate.

Sample (.NET) Source Code

In C#, the way you call ShellExecute is to use Process.Start along with UseShellExecute = true:

private void button1_Click(object sender, EventArgs e)
{
   //Public domain; no attribution required.
   ProcessStartInfo info = new ProcessStartInfo(@"C:\Windows\Notepad.exe");
   info.UseShellExecute = true;
   info.Verb = "runas";
   Process.Start(info);
}

If you want to be a good developer, you can catch when the user clicked No:

private void button1_Click(object sender, EventArgs e)
{
   //Public domain; no attribution required.
   const int ERROR_CANCELLED = 1223; //The operation was canceled by the user.

   ProcessStartInfo info = new ProcessStartInfo(@"C:\Windows\Notepad.exe");
   info.UseShellExecute = true;
   info.Verb = "runas";
   try
   {
      Process.Start(info);
   }
   catch (Win32Exception ex)
   {
      if (ex.NativeErrorCode == ERROR_CANCELLED)
         MessageBox.Show("Why you no select Yes?");
      else
         throw;
   }
}

Bonus Watching

• UAC – What. How. Why.. The architecture of UAC, explaining that CreateProcess cannot do elevation, only create a process. ShellExecute is the one who knows how to launch Consent.exe, and Consent.exe is the one who checks group policy options.