Can outfits other than Law Dogs start with Gomorra Jail?
From the rulebook, page 14:


  Once players have revealed their outfits, they search their decks for up to
  five dudes—either from their outfit or drifters


(Bold added)

Dudes from other factions can be in your deck, but not your starting posse. Hence if you are playing something other than Law Dogs, there is no way to have a Law Dog in your posse for the Jail to start "in place of".