Here is another photo of #20 loading at Seattle. Note that the boom of the dock side crane is at a steeper angle as it is lifting the locomotive off the rail car. They likely lifted the locomotive off the flat car and then boomed down to shift the load out far enough to reach the ship. It looks like they also have a line attached to the front
None of the photos show the rigging clearly enough so see for sure how it was done, but it looks like the dock side crane was doing it all. Again it is not clear enough to see, but the skids shown at Skagway might have been on the ship when the locomotives were loaded. The ship is not very big and they might have loaded the locomotives cross ways because they would have had a balance problem if they loaded them one at a time on the sides of the deck. In 1977 they had this problem with the barge that brought brought the stuff down to Seattle, and had to quickly throw some more weight on to keep the barge from listing. We got a pair of heavy arch bar trucks out of the deal.