I don't know about cdbkup, but the following probably helps:
yes '' | cdbkup 0 --label=TEST -s 4 0,0,0 /home
The "yes" command produces a continuous stream of 'y' characters followed by 'enters' by default. When you pipe ( '|' ) this to another command it answer 'y' to all questions the command ('cpbkup' in your case) asks from the standard input ("stdin"). You can have 'yes' output a continuous stream of -say- '#' by using "yes '#' ". Or pass it an empty character ( '' - two single quotes) to pass a endless stream of "enters" to the other command.
Hope this helps.