Place the preserves in a small saucepan over medium-low heat, and cook 10 minutes or until melted. Keep warm over low heat.
Combine salt, oregano, garlic powder, and pepper; rub evenly over pork. Place pork on a rack coated with cooking spray; place rack in a shallow roasting pan. Bake at 425° for 30 minutes. Brush 1/4 cup preserves evenly over pork. Bake an additional 10 minutes. Brush remaining preserves evenly over pork. Bake an additional 10 minutes or until thermometer registers 155° (slightly pink). Let stand 10 minutes before slicing.