You could hook up compressed air to the wet bay water inlet, I use 40 PSI. Then set my washer to a cotton cycle with water temp setting set to full hot and start the washer. I hear water entering the machine, then it will become just air. Then I reset the cycle by pressing and holding the "Start" button for a few seconds until the lights come on, then release. Then change the water temperature to full cold and restart the cycle. Again it will initially admit some water and then you hear the air. Then lastly reset the cycle using the "Start" button again and switch it to the "Drain" cycle and restart the machine which will pump out the drum.
To help ensure the pump and drain line protected you might consider pouring some antifreeze into the drum and run the "Drain" cycle again to push antifreeze through the pump, drain line, and even into the drain trap for the washer.