Quick way to create a SQL Server 2008 R2 installer with integrated SP1 (Slipstream)

For Spanish version visit this link Forma rápida de crear un instalador de SQL Server 2008 R2 con SP1 integrado (Slipstream)
With the Slipstream funcionality we can integrate Service Pack or Cumulative Updates to the SQL Server installer, this save much time, specially when you need to do multiple installations.
This guide is a modification of How to slipstream SQL Server 2008 R2 and a SQL Server 2008 R2 Service Pack 1 (SP1), to which I add a .bat file to save time.
This guide is for the English version of SQL Server 2008 R2.
  Read more of this post