It does all off that automatically.
Before running the workflowe I create the Storage Policies, define the subclients that point to them, attach the USB drive, and create a folder on the USB drive for the copy to go on.
Then I execute the workflow by typing in the path to the USB folder in the LibraryPath field, selecting the new Storage policy in the StoragePolicytoSeed dropdown box, and selecting the GDP of the server you want to seed to. then hit OK and it does the rest.
I would recommend against running any backups before the seeding process as the workflow will run the backups as part of the process.