Do you want to reinstall JamPacks that you previously purchased?
The JamPacks are no longer available for download, and not all your old installer DVDs will work with Lion, sorry.
One options to get installers that work with MacOS X Lion is to buy Mainstage 2 from the AppStore. This will install all Jam PAcks in a way, so that the loops and instruments are installed for Logic and GarageBand as well. Mainstage is much lesss expensive than any of the JamPacks used to be.