Hey,
You may want to read up on this at the following URL:
http://technet.microsoft.com/en-us/library/cc280547(SQL.100).aspx
It talks about Migrating from SQL SSIS 2005 to SQL SSIS 2008, but provides a method to do backing up of your packages.
From what I read, you would have to export your packages to file system.
Hope this helps
~PD