Make the pork: Combine the brown sugar, coffee, chile powder, 2 tablespoons water, the molasses, 1 1/2 tablespoons salt and a few grinds of pepper in a 6-quart slow cooker. Add the pork and toss to coat. Cover and cook on high until the pork is tender, 5 hours.
Meanwhile, make the slaw: Combine the coleslaw mix, pineapple, mango, scallions, vinegar, chile and 1/2 teaspoon salt in a bowl; toss. Cover and refrigerate at least 2 hours.
Transfer the pork to a bowl using a slotted spoon; let cool slightly. Strain the cooking liquid through a fine-mesh sieve into a saucepan; bring to a boil and cook until reduced by half, about 5 minutes. Shred the pork using two forks, then add the reduced cooking liquid and toss. Cover to keep warm.
Assemble the sandwiches: Heat a medium nonstick skillet over medium heat. Add the Spam and fry until golden, 2 minutes per side. Serve the Spam, pulled pork and slaw on the rolls.