How should I position surrounds (7.1) in this room??

My room is 24 ft. long X 14 ft. wide. The front wall is at one end with the listener seating 12 ft. away. As I have a brick wall down one long wall in-wall spks are impossible, so I would like to put in in-ceiling surround spks. What would the placement positions be for the best effect. I would also like listening to audio alone on this setup? Thanks!!