Application Development Software

I am using iMS 5.2 and want to migrate a Domain abc.com to def.com.
I have created the second Domain and added the e-mail address of this domain as alternatemail address for each user of first Domain. THis leads to mail forwarding to second user.

However, I want that after the migartion is over there should be single mail box for each user and not multiple ones.

The users should have mailboxes in migrated domain def.com and ultimately I should be able to delete the mail boxes of abc.com

So I feel there must be a smarter way of doing the same.
LIke renaming a Domain or creating a Domain alias so that I will create a new Domian
def.com and somehow migarte all users from abc.com
Move mailboxes from abc.com to def.com
Delete users in abc.com along with the mailboxes
Create a Domain alias of new def.com by old name abc.com so that mails sent to old address come to the new address and mailboxes.

PLease suggest a better way ...am I thinking in rt path...what is the standard procedure to migrate a Domain to a new name???