Here is how I visualize ventriloquism...Did you ever eavesdrop on a conversation that sounded exciting, just because it was? Well that's what ventriloquism is, its eavesdropping on a juicy and exciting conversation between the ventriloquist and his figure. Its like someone talking on a phone and you don't want to miss one juicy morsel of this, its funny, its sad its all the moods. Its exciting, it grabs your attention, It could take place in a supermarket, a Laundromat, on a cruise ship, it could take place everywhere, and you are invading the funny stuff.
So while writing your material write it in that form to give the impression that a conversation is going on and without you knowing your being intruded upon.