When smoking a pork roast you want to keep a close eye on the temperature. Ideally your pork is done cooking when the temperature of the center of the roast registers at 185 degrees F. One problem is that the meat can really dry out the longer it cooks. Since the outside of the roast will be hotter than the middle, you can use this heat to finish off the meat outside the smoker. Once the center of the meat is around 175 degrees F. take it out of your smoker and wrap it tightly in several layers of foil, making sure to keep the roast warm. There are several ways to do this. One of the simplest ways is to place the meat in a small cooler. The cooler will hold in the heat, allowing it to reach the right temperature without cooking it any more. This is also a great way to hold the meat until you are ready for it.
Wrapped tightly the meat will steam a little making it easier to shred.