Predrill holes in the concrete block at each chalk mark, using a hammer drill and a masonry bit. The holes hold a plastic anchor into which you can install lag eye bolts. The hole must be as deep as the plastic anchor length — usually 1 to 2 inches. The plastic anchor must be as long as the eye lag bolt threads, and the eye lag bolts must be long enough to protrude 3 inches from the wall after installing the bolts in the anchors.