It is a snug fit depending upon how they are trimmed, but it can be done. I set up a wall in my kettle for smoking using fire bricks that takes up about 1/3 of the space. I pile them as deep as I can with chunks of wood buried so that the cooking grate fits right on top of them. Some people will start start at one end but I just dig a hole in the middle for my lit coals. I put the vent on the opposite end from the coals over the top of the ribs to get it to draw smoke across. Orient the ribs in opposite directions from each other and rotate them to help with even cooking. I also use a foil pan under them. A little water in the pan is optional.
WSM, 99 & 09 Performers, 2-OTG, SJG mini WSM, Summit 420, Q100, Akorn, and Schwenkgrill