Universal Messaging Migration

I know that UM migration is supported later from webMethods 8.2.
If so, How to migration from under WM8.2?

What is additional task to perform migration except run the brokerjndimigration.{bat|sh} / brokerjmsmigration.{bat|sh} script?
(E.g. user authority, properties, settings and so on…)
And, How can i ?