Never done one in a crockpot but have used this method in the oven "before" I got my egg.
From another website.
Carolina Pulled pork
1 pork shoulder or butt, bone in or out--any size--the cooking time is the same for a 3#or 8# piece.
BBQ rub of your choice (I will post mine if you want) or just rub the meat with a mixture of coarse ground black pepper and brown sugar. Let marinate 8 hours or overnight.
Method 1--IF you have a smoker that can control the temp (I have a sidebox smoker and can keep the temp at 200*-250*) smoke the meat for 4 hours, keeping the temp low. Then place the meat in a 250* oven for 4 hours to finish. It will be meltingly tender and have a wonderful smoky flavor.
Method 2 (and this is the one I have really used for 30 years). Place the meat in a 225-250* oven for 8 hours uncovered . I have often done them overnight. It will still have the melting tenderness. You will have to slap your hands to have any left over as you take it out of the oven.
When ready to serve pull chunks of meat off and then "pull" the meat into shreds by pulling between 2 forks. Do not discard the fat--mix it in. This is not a low fat dish and to really enjoy, use it!!! The pork can also be chopped.
For a traditional Carolina serving method very lightly moisten the pulled meat with sweetened vinegar (1 qt. vinegar + 1/4C sugar and 2TBS coarse black pepper). It should be so little that you don't even know it has been added.
To warm before serving put the vinegared meat in a pan (black iron frying pan is good or Le Creuset) and cover tightly. Heat at 250* until heated.
To serve, offer bbq sauces, cole slaw (in the Carolinas, it goes ON the sandwich), baked beans, rolls, and banana pudding. For fall bbq's Brunswick Stew is also offered.