Assuming you have installed SQL Server 2012 and SQL Server Data Tools, you should be prompted to update the solution when you open it. I also assume your 2008R2 builds are configured for signing.
After going through the update wizard, you need to do a few things:
Modify your custom tasks and components to configure the .NET 4 Framework in each of the project properties, in the Application tab, within the target structure.
Update the build links in each of your projects to point to the appropriate SqlServer Dlls.
Create and copy the project DLL to the appropriate directory, depending on which components you are updating, i.e. Program Files (x86)\Microsoft SQL Server\110\DTS\PiplelineComponents Program Files (x86)\Microsoft SQL Server\110\DTS\Tasks
Register your components in the GAC.
Close Visual Studio and then close again; open your SSIS packages and update the SSIS toolbar by right-clicking on the toolbar and the selected Refresh Toolbox .
You can get more information here http://msdn.microsoft.com/en-us/library/ms345161.aspx
source share