If the steering problem is the cable, there's not a grease fitting. You'll need to replace the cable or try some of the home-brew remedies, such as installing a grease fitting or attempting to use a motorcycle cable greaser.
Early problems with the steering cable are a sign that the cable fittings are being washed in water. If you want your steering cables to last, you will have to figure out why it's getting bathed and fix it.
Some boats, such as the Tige 21V, have a chronic problem with this. Water pools in the hull around the middle, well in front of the bilge pump. When you take off, the water rushes to the back and washes the oil off your steering cable.