I have a 2014 Bounder 35K with Icemaker. I wondered the same thing when we first bought ours.

I have found two ways to do it. #1  The easiest way is to drain the fresh water holding tank completely

I then put 3 gallons directly into the holding tank, with the fridge on and the icemaker onI just let it run

until it's making pink ice. You have to use the water pump not city water connection. It's a longer process than the other option. 

#2 you can remove the cover on the left hand side of the ice maker and advance the gears by hand until the silver arm starts to move up. You might also hear the liguid pumping in. It takes a few advancings to get the antifreeze there. I don't really care for this method myself because I was afraid of stripping the plastic gearing.

Someone with more experience may have an alternate method, 

Best of luck, Don