• In testing this, I created a new VS 2008 project, which gave me access to its properties (right click on name). Found the debugging section and its 64 bit setting and changed it to false. This let me add the DTSX to my project. However, VS 2008 gave another error concerning the install of SQL Server. Seems it wants Integration Services running on the workstation where I was working. Tried the entire process on my SQL Server box (where IS is running) and it worked just fine.

    End result, creating a new VS 2008 project on a box running IS and turning the project's debugging 64 bit setting to false let me add and modify the existing DTSX.