I think its not supported till now.
Look at the below post.
tr to migrate this file
I am also doing the same task
and failing to get the custom users
If you can tell me what else you did ,It will be helpful.
I have copied the custom directory data xml from one server to another and restarted the services and restarted the server too
but i am still not getting the users in my custom directory.
Please help Its Urgent