Hey, you should all be proud of me that I made it this close to actually releasing the game on Halloween. ;)
But seriously, I wanted to give myself plenty of time to weed out problems since I've never attempted multiple launch options with Steam before. BUT... it looks like everything works! :)
Once your game updates you should now have two launch options- the main game (updated to 1.1), or the Halloween Edition!
Enjoy, and Happy Halloween!
NOTE: For people having issues with finding the Halloween Edition: Try relaunching steam, and then it should give you the option to launch the Halloween Edition after you click Play.
The other way you can do it is to right-click Five Nights at Freddy's 4 in your games list on the left side of your Steam window, the Halloween option should appear there as well.