Set up a good heavy duty step ladder, like a Little Giant, on the dock a few feet higher than the finished elevation. Lay a 4x4 under the joists and attach 1 end of the comealong to it and the other to the ladder. A chain hoist might be a little better suited for this.
Another idea is to attach some long lever arms to the joists, extending upwards and toward the bank. Tie on a rope and pull down, levering the whole structure up.
Whatever you do be safe. 1 trip to the emergency room will cost you more than a crane rental.
