I'm not sure on your exact setup but can you use the water pump to fill the ice maker line. I usually winterized by taking a short hose and attaching it to the entry side of the pump and then put the hose into a gallon of antifreeze. I then have my wife open and close each faucet until the antifreeze appears. The ice maker would be the same way. We don't use our ice maker, so I have it turned off at its source. I also have the washer dryer turned off at the source. If we use it, then I still use the same method to winterize it.