sorry I don't have any real documentation but I have a snippet of powershell that explains it pretty well here
this comes from a user creation script I wrote back when they removed the unix UI.
I was using Get-AdUser and discovered that the properties still existed but you have to manually shove those in, when an sssd "domain bound" linux machine has a user with these props login, they get the defined UID and GID and homefolder etc.
basically the "OtherAttributes" on the ADUser object is a hashtable that holds all the special additional LDAP attributes, so in this example we use $otherAttributes to add all the fields we need, you can do the same with "Set-Aduser" if you just wanna edit an existing user and add these props
the @thing on New-ADuser is called a splat, very useful if you're not familiar, it turns a hashtable into arguments
Yep. i imagine the long time between initial announcement and still waiting, is getting it right for realease. At least I hope that is why it has taken so long