When smoking a pork roast you want to keep a close eye on the temperature. Ideally your pork is done cooking at a temperature around 185 degrees F. in the very center of the meat. One problem is that the meat can really dry out the longer it cooks. Since the outside of the roast is going to be hotter than the middle you can use this heat to finish off the meat outside the smoker. When 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. Now you will want to keep it warm. There are several ways to do this. One of the simplest ways to do this 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/pull