From phpBB3 to vbuletin 4
 

I'm considering helping a friend to upgrade his phpBB3 forum to vbulletin4. But as I'm not a pro and don't perfectly understand the documentation (http://www.vbulletin.com/docs/html/) about the Impex.
How easy is it? How risky is it?
Would a professional installation (option when buying license) be able to do this for me?

Thanks,
Christophe