Adding custom shortcuts to Metro:
  Hopefully you already know how to "Pin / Unpin apps to metro from the "all Apps" area. All you need is the location of where to put your shortcut.

In Windows Explorer Copy/Paste this location in your address bar

%appdata%\microsoft\windows\Start Menu\Programs\

Paste the shortcut to your application, batch file or shortcut file here

Then you can "Pin it" from all apps area to Metro