At the risk of seeming to be a smartass (well, I am, but that’s another issue) your question is not quite clear.
Are you asking whether or not the server can be migrated in a lab environment, and then plugged into the production environment?
If so, probably, but you’ll still need to re-add the server to the production domain controller.
What I’d recommend is that you use Norton Ghost (or some other disk cloning application) and make a duplicate of your 5.5 Exchange server, and then test that in the lab to get past all the “gotchas” so that you’re up on the learning curve of what all is involved in your particular migration.
Then, when you’re confident, clone the 5.5 server once more for backup purposes, and do it over the weekend to minimize user impact, and allow your self time in case something goes wrong
Hope that helps,