Make 3 balls of aluminum foil and place them in the bottom of your slow cooker. These hold the chicken off the bottom so the hot air can circulate all around the chicken and so it's not stewing in its own juices.   

Rinse chicken, including the cavity, and pat dry with paper towels.

Place the chicken on its back so the breast is facing up and the legs are on the plate. Pull the skin up all around the chicken. Do this by sticking your hand between the skin and the breast. Slice a few garlic cloves in half lengthwise and stick them under the skin. You can also arrange a couple sprigs of fresh herbs like rosemary, thyme, and/or sage under the skin. This makes a very pretty chicken when it's all cooked and adds a lot of flavor.

Rub salt-based seasoning very liberally onto the skin of the chicken. Place chicken breast-up on the foil in the slow cooker, cover, turn heat to low, and leave it alone for 7-8 hours.