I haven’‘t done a migration from jabberd but I did a migration of ~100 users from Jabber Inc.’‘s JCP server and it was a pretty straight forward process. I wrote a little program that went through all the user data and created an xml file that I could then import into Messenger using a plugin I created. I hope to release the plugin at some point but it needs some polish before doing so, but if you’'d like to use it let me know and I can let you know how to get and use it.