I've never had much luck with lube tools.
The simplest way I've found to lube cable is to disconnect the upper end, clip the corner out of a ziplock bag so it just fits over the cable, using at least 2 zip ties attach the bag tightly to the cable keeping the ties on the metal ferrule of the cable with the blocks on opposite sides (cuts down on leakage), rig the bag so it remains upright and no drips will end up on the bike, put an ounce or so of ATF or even motor oil into the bag, zip bag closed place a towel under the lower end of the cable to catch excess oil and leave overnight. The next day make sure oil is dripping or has been dripping from the lower end of the cable, remove the bag, clean and reattach the cable and you're done.
This does not work with teflon lined cable sheaths such as those found on Honda ATV's.
