You may have noticed that there aren't any specific instructions from Microsoft on how to get the Visual Studio 2013 update download if you need to create an administrative layout. If your firewall or proxy settings don't allow you to access the download center, you'll need to follow outlined steps.
Related: New Features in Visual Studio 2013
A blog post from by Jill McClenahan via the MSDN SQL Server Data Tools Team Blog provides guidance.
For additional information, see: Creating an administrative install of SSDT update for Visual Studio 2013