Download the Tools from here: http://msdn.microsoft.com/en-us/data/hh297027
During the installation, if you encounter the following error message:
[1644:1654][2013-02-27T12:35:02]: Registry key not found. Key = 'SOFTWARE\Microsoft\DevDiv\VS\Servicing\11.0\intshelladditionalres\1033'
[1644:1654][2013-02-27T12:35:02]: Registry key not found. Key = 'SOFTWARE\Microsoft\DevDiv\VS\Servicing\11.0\IsoShell'
which means you need to download and install the visual studio 2010 sp1(VS10sp1-KB983509.exe) first from here: http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=23691.
Then you should be able to finish the installation of SQL Server Data Tools 2012
