You can definitely do it! A smokey Joe will fit inside a CG or WSM, right?
In the past I had really good luck indirect grilling things like pork tenderloins or small racks of ribs on a Smokey Joe, but as Brad said - it's a challenge. They're great little grills.
The best bet would be to two small piles of coals on opposite sides and the butt in the center (I'm not sure the lid would fit on if you moved it out of the center). I used to put three or four unlit coals and some wood chips on each side and then put three or four lit coals on top of that to do ribs at around 300. For temp you could drill a hole in the lid at grate level and permanently install a thermometer (can't beat modding a Smokey Joe!) You'll need to keep a close eye on it, but it should work.