Suppose you want to burn the content of /my/directory/datas at the root of the DVD, you need to type:
$ growisofs -dvd-compat -input-charset=ISO-8859-1 -Z /dev/hda -R -J -pad “/my/directory/datas”
Remember that input-charset is setted to the right value. If you do not define it, your default system charset will be used.