Oh, I actually have that set up under nautilus.
System -> Preferences -> Look and Feel -> Nautilus Actions Configuration
File, new action.
Context label - Shred
Tooltip and icon you can set yourself.
Check enabled, uncheck read-only.
Go to the command tab, and use the following:
Label: Shred
Path: shred
Parameters: -f -u -v -z %M
Conditions tab:
Appears if selection contains: Both
Check "Appears if selection has multiple files or folders"
After that, go to file, save.
Enjoy
Note, to access shred, you can select multiple files and folders, right click, and click on shred.