It seems the you must be physically wounded to turn into a husk. I had a legendary speardwarf last quite awhile against a swarm of about 20. Then he got a bruised leg. Goods news is that he still hates Husks. Suggested strategy for tradional combat methods is to drop in a heavily armored sword/axe dwarf in on his own, as in groups you'll eventually get one turned and then he'll slice your army a new one. Don't bother training marksdwarves, despite Husks making great target practice, as everything above ground will soon be a Husk.
I believe that, short of excessive dismembering, Husks are effectively immune to normal combat.
If you embark on a site with Creeping Dust ensure quickly that all parts of your fort, even theoretically "outdoors" areas are airtight. Make sure your fort can be closed off from the outside world at the drop of a hat. Kill ALL animals you were foolish enough to bring with you. A kitten is as dangerous as a bear when its an immortal plague machine. Plan on having a relatively small fort. One day RNG will make a cloud pass over an invasion force or a horde of migrants. You will never receive another migrant once this happens, as they will be quickly huskified.