you do a 180 and tap A D A D whilst holding W. I can do it for a few seconds every now and again but it's not BM enough
i'd post a link to a vid of it but i got an infraction last time for helping out people on this forum so yeah just search on youtube dead by daylight moonwalk and look for the video from sept 2017.
there was an older moonwalk but it got patched, this is the new one which is harder to do