When you say you are using AD, it sounds like you really mean you are using Windows Authentication. It should work using AD/LDAP over forms authentication.
Technically there is no way to make WLW use Windows Authentication, in the article you posted they are providing a way to bypass Windows Authentication.
In mojoPortal I "think" a different but similar workaround is possible. When using Windows Authentication, we automatically create a mojoPortal user in the database and a random password is generated and assigned to the user though he doesn't need that password for signing into the site with Windows Authentication, he could use that password and his user name for WLW. You can think of this random user password as the equivalent of the user api key in telligent.
You can try it out by looking up the password in the mp_Users table in the Pwd field. So the user could enter his username from the LoginName field and his password from the Pwd field in WLW when configuring the blog. He will only need that to set it up since WLW retains that data.
Hope that helps,