Heat gas or charcoal grill. In small microwavable bowl, mix cherries, onions and whiskey. Microwave on High 30 seconds or until hot. Let stand 10 minutes. Stir in preserves.
Cut pork tenderloin lengthwise almost but not completely through to other long side. Open tenderloin to lay flat; sprinkle with salt. Spread 1 tablespoon preserves mixture on each side of pork.
Place pork on grill. Cover grill; cook over medium heat 10 to 12 minutes, turning once, until pork has slight blush of pink in center and meat thermometer inserted in center reads 160°F. Microwave remaining preserves mixture on High 30 to 45 seconds or until warm. Cut pork into 1/4-inch-thick slices; serve with warm preserves mixture.