2021 Discovery LXE 40M

First time winterizing a washer. We have a Whirlpool washer and in the manual, it tells me to add a quart of antifreeze to the drum and run for 2 minutes on normal cycle to winterize the washer. Easy enough! However, there is no mention about the drain. I'm assuming there is a trap between the drain hose and grey tank. Any suggestions on how to drain, or push antifreeze into the drain tube and trap? 

Thanks,

Doug