Create Users from Imported Comments

I’ve recently decided to merge my WordPress blog and my old LiveJournal blog. My LJ blog has friends-locked posts and I’m keeping that format in WordPress when I import them.

What I would *like* to do is associate the author of each comment imported from LiveJournal with a new user account in WordPress so they can continue to view those Friends Only posts and track their old conversations as well.

For example:

If Tom, Anna, and Joe all commented on my LiveJournal posts, when I import my LiveJournal posts I’d like user accounts created for each of them and to have those user accounts automatically associated with their imported comments.

Is there a simple way to do this? Or am I limited to creating the user accounts separately and editing comments on the back-end through SQL to associate them to the user accounts?

Thanks!