So you won't be able to create a good protection (bad sectors, illegal toc...).
If it's a movie DVD, you can easily add region codes to your IFO files, some software even let you put CSS protection on it (not sure about that though), but these are more annoyances than copy protection.
For a data DVD, i don't know... all you can do is, i think, screw up the file system so that no one can copy some files back to HDD, but even nero will be able to copy such a dvd.