Did you even look at the diagrams? If you can't make heads or tails of those wiring diagrams you really need to consider letting a shop finish the job. There are some very complicated diagrams for these cars, but, next to the cigarette lighter those are the easiest.
Pull the grills for the hatch speakers and make sure they're even there. If they are there then yes, they're supposed to be wired with the rear seat speakers. If the speakers have been replaced at some point they may be mismatched and the hatch speakers require more power than the rear seat speakers in which case you won't ever hear them; they'll only whisper when the rest of the system is screaming.
EDIT: and you even asked specifically for diagrams... lol.
