I've tried smoking pork butt many times, and although I've had friends who have the patience to spend the necessary twenty hours caressing the smoker, including through the middle of the night to keep it stoked with charcoal, chips and water, I'm not there yet. However, I have a fabulous slow-cooker alternative that will turn out an awesome pork butt, with lots of flavor and falling apart, in twenty hours with almost ZERO attention! Read on ...
Don't be afraid to use the pork butt for bbq, chili verde, etc. 
Evenly rub the pork butt with the mixture of pepper, salt and cumin.