Perform a basic devotional offering rite to Dionysos and then watch a bunch of thematically appropriate movies.
I recommend doing four sets of three movies in the following categories: horror, comedy, fantasy and drama.
At the end of each set have the participants vote their favorite of the three.
Encourage discussion, especially about the Dionysiac or Starry Bull elements of the films.
You may also hold contests where participants give their best dramatic readings of ancient Greek plays and poetry. These should get better in direct proportion to the amount of wine the participants consume.
Since this was a multi-day festival in antiquity you can either do a category a day for four days or do them all in a single marathon movie-watching session. Alternately one can just pick their favorite categories and ignore the rest.