Allied makes what I call a bar-hanger light box, most are probably familiar, if you find one with recept., let me know. This would be my recomendation if you can find it. It is a [back] pain having to horizontally mount recept. in a baseboard. So far, for me, it has been hammer and nails. Are you going in the baseboard where you are essentially raising the bottom plate with scrap lumber, or are you having to cut blocks and nail them in? A nail gun would probably better serve the latter so you won't have to hold the block and swing the hammer at the same time.