In a small mixing bowl, combine together the olive oil, Italian seasoning, seasoning salt and minced garlic.
Take 4 pieces of aluminum foil and roll each piece into a ball. Place the balls of foil on the bottom of a 6 quart or larger slow cooker to act as a roasting rack for the chicken (you may also use a roasting rack for your slow cooker)
Rub the chicken on both the outside skin and under the skin, using all of the olive oil seasoning mixture.
Place the chicken in the slow cooker on top of the foil or roasting rack, breast side down.
Cover and cook on HIGH for 3 to 4 hours or until the internal temperature of the chicken registers 165°F (74°C) when inserted into the thickest part of the thigh.
Remove chicken from slow cooker and allow to rest for 10 minutes before carving and serving.