Reading this thread: http://www.sqlservercentral.com/Forums/Topic836951-146-1.aspx,

the packages are stored in the [font="Courier New"]sysdtspackages90[/font] in the msdb database. You can take the xml and store it in a .dtsx file and have the original package. I've never done it this way, but it sounds like what you're after.

HTH,

Rob