dsquery user “OU={your target OU},DC={your domain},DC={your domain extension}” | dsmod user -pwdneverexpires yes
Update: Note: If your OU has more than 100 users in it you need to add the ‘-limit’ flag, and set it to a number greater than your actual amount of users, e.g.
dsquery user “OU={your target OU},DC={your domain},DC={your domain extension}” -limit 2000 | dsmod user -pwdneverexpires yes
