My recent project involved using a DSN as the connection string in SSIS. The challenge of the project was that I only had the 32-bit version of the driver to create the system DSN but the server was a 64-bit server. In Administrative tool there IS a 32-bit version of the ODBC editor so that was not a problem.
However, in order to make everything work in SSIS I had to do 2 things.
1) To debug in BIDS I had to change one of the solution properties. Under Debug set the Run64bitRuntime option to False.
2) In order to use the 32-bit runtime once the package was set to run as a SQL job in SSMS I had to check that option on the Step setup on the Execution Options tab.
After this everything was running smoothly.