I had some old track slides. I took 2 of them, and connected them with a 1" bar of aluminum. I then fit a piece of the really coarse (red) scotch-brite pad between them. Then, I taped an old hinge to the top of a can of McLube Sailcoat, so that when I pushed the hinge, it activates the sprayer. Finally, I taped the can of McLube to the 1" aluminum bar.
I attach a halyard to the top track slide, and a line to the bottom and feed the whole contraption into the track. I also have another line attached to the hinge, so that I can use the spray can remotely.
I pull the thing up and down the track a few times, so that the scotch brite can do it's thing, then, starting at the top, I pull the whole mess down the track while activating the sprayer.
Works like a champ!