I would look into doing it like you would with a gas powered appliance in a house. Use a 4-6" pipe with a metal boot to go thru the roof. I have my backwoods fitted with a rectangle register duct to transition from a rectangle that fits over the exhaust and allows me to connect a round flex pipe to it. I use that if i have to cook under a pop up tent and want to keep the smoke out.
That being said I would be cautious of not keeping a close eye on that thing if i had it inside. Bad things can happen. I hate how my fatboy likes to spill hot coals when you have to slide the basket out to refill. Also after cooking on it for a year I somehow had a lapse of judgment in setting my dampers in the middle of a late night cook. The pit got to about 500*. Luckly it did not sustain any kind of damage and was outside. It did cause a grease fire to happen once I opened the door and air was allowed in. All Im saying is think twice and if you must be really careful.