An updated version of the Data Mining Add-ins for Excel has been released as a part of the SQL Server 2012 Feature Pack.
Feature Pack page
Add-ins download page
This update provides support for 64-bit editions of Office.
This release of the add-ins does not require installation of SQL Server 2012. In other words, you can use these add-ins if you want to use the 64-bit edition of Office but connect to 2008 R2 instances of Analysis Services.
If you have an existing older version of the add-ins, the installer will offer to upgrade.
SQL Server UE, Data Mining