Dionysus is never supposed to have returned from the dead. There is one, single inscription that that claim is based on and it describes Dionysus as "a god who renews himself and returns every year rejuvenated". If you people know anything about fertility and agriculture gods you know that this means that he doesn't even die.
Second, the myth about cannibalism is this:
Dionysus as an infant was set upon Zeus' throne to play at being Master of the Universe. As he sat there, some of the Titans -- bad boys of Greek mythology -- snuck up with some toys and distracted him. While Dioysus was thus distracted, the Titans picked him up, tore him to pieces, and boiled and roasted everything but his heart and ate it. When Zeus got wind of this, he became ticked as he often did, and blew the Titans to smithereens. As the story goes in a later version, from the ashes of the Titans came forth the race of men; D himself was "eventually restored to a new life" from the heart that was left over.
Sadly for this argument this myth is "a myth of unknown origin and contested antiquity". On top of that, it is no where near the same as Eucharist in meaning or practice.
Third, Dionysus was not born of a virgin, that is simply a forgery by Freke and Gandy in The Jesus Mysteries. On top of that, they don't even claim that Dionysus is of virgin birth, only a "miraculous birth".