You need a cable luber: Yamaha Cable Luber Deluxe I recommend one like the Yamaha luber with 2 screws. You may see lubers with 1 screw, but they don't clamp on well, and are even more messy than the 2 screw luber. You end up wasting about 1/2 of the lubricant even with a well fitting luber.
You have to take the cables loose from the throttle and trim system to use the luber. The cable fits into the rubber groove in the luber and the end of the luber goes over the cable housing. Then you tighten down the screws and squirt in the cable lubricant in the small hole on the side of the luber. The lubricant is forced around the cable and into the housing. Of course it is impossible to get a completely air tight seal, so some lubricant squirts out the sides of the luber. I wrap the whole thing with electrical tape and put a rag over it, because you will still get excess lubricant squirting out all over the place. :violent-smiley-028:
I use Yamaha Lubezall to do the cables, because it is fairly thin and will penetrate all the way to the end of the cable if you do it right and on a regular basis. I can get the lubricant all the way to the end of the trim cables at the back of the ski with this luber.
On my ski the reverse has a solid stainless steel rod, so you can't use the luber. I just smear marine grease on both ends of the reverse system.