Preheat a gas grill to medium (about 400°F) on one side, or push hot coals to one side of a charcoal grill. Combine first 3 ingredients in a small bowl. Starting at the neck cavity, loosen and lift chicken skin from breasts and legs with fingers. Rub oil mixture under loosened skin. Open beer can; pour out 3/4 cup beer, reserving for another use. Place chicken upright onto can, fitting can into cavity. Pull legs forward to form a tripod, so chicken stands upright. Place chicken upright on grill grate over unheated side. Cover and grill 1 hour and 30 minutes or until a thermometer inserted in thigh registers 165°F, rotating chicken once. Combine mustard, honey, vinegar, and tomato paste in a small bowl. Place chicken and can on a cutting board; let stand 15 minutes. Remove and discard skin and can. Cut chicken into pieces; place on a platter. Drizzle with sauce, and sprinkle with parsley.