Here is how I moved my jobs to cold storage using the Shelve Project plug-in
WARNING the Shelve Projects plug-in does not maintain data for the Job Config History plug-in. If you unshelve your project, the configuration history will be empty.
WARNING the Shelve Projects plug-in does not copy your builds if you have modified the config.xml to change buildsDir. (Note: I have not tried this on a clean unmodified installation - so I cannot guarantee it ever saves builds).
Then later you can copy those files back, and the "Shelved projects" will now show the project you retrieved from cold storage.
Unfortunately, this process loses the Job Config History.