Any process in which a horizontal cell is transported to, and/or maintained in, a specific location within the inner nuclear layer (INL) of the retina. A horizontal cell is a neuron that laterally connects other neurons in the inner nuclear layer (INL) of the retina. Targeting of retinal neurons to the appropriate lamina is vital to establish the architecture of the retina. [ http://www.ncbi.nlm.nih.gov/pubmed/18094249 http://purl.obolibrary.org/obo/CL_0000745 ]