grab some marroon scotch brite pads,(from a buddy shop) or crappy tire, green ones will work.
remove the springs from your shocks and sand by hand.
sand enough to remove the gloss and give the paint somethin to stick too.
buy some flat or gloss black paint from crappy tire etc, wash the springs down with brake cleaner or soapy water and allow to dry.
now painting theses might take some effort because theres so many different angles, to cover with paint.
due lots of coats and maybe some clear if you want to.
now remeber these were probly powder coated from the factory soo if you hit to many sticks the paint will chip.
i suggest lots of clear, so the finish lasts longer.