Heat Kamado grill to 250F using a heat diffuser and a drip pan large enough to catch the drips from the butt.
Place butt in grill over directly on the grill over the drip pan.
Use a thermometer that will tell you the temperature of the meat while you are cooking.
For this cook, at 120F, I wrapped the butt in foil. The butt had been in the grill for 2 hours.
At 190F, pull the butt out of the grill wrap with another layer of foil and place 9x13 cake pan.
Put a towel in the bottom of a cooler large enough to hold the cake pan. Add the foil-covered butt and cover with a couple more towels. Let the butt rest for 1 to 3 hours.