Many customers want to install Books Online (BOL) when working with SQL Server. Generally I always think it's a good idea.
Not all environments though, allow external connectivity for the systems where the clients want to install BOL.
A friend of mine Rob Sanders documented how to install BOL in an offline method a while back:
http://sanderstechnology.com/tag/sql-books-online/#.VBTu3vmSx8E
The problem with this was that the T-SQL Reference documentation was not included in the download for offline installation. Given the T-SQL language reference was the major reason that most people wanted to install BOL, it all seemed quite pointless.
I got the good news this week from Jeff Gollnick in the documentation team that the August release now includes the T-SQL language reference and that it's available here:
http://www.microsoft.com/en-us/download/details.aspx?id=42557
That's great news.