How do I transition multiple installations to a single Multisite installation?

I have a client who runs 8 different blogs, currently on 8 separate installations of WordPress. I’m trying to encourage them to move to a single MS installation instead to make it easier (mostly on me) to maintain the different sites, themes, and mix of plug-ins. Unfortunately, I shied away from MU for the longest time, and now I have no idea where to start with MS.

I’ve used WP-Hive in the past because it allowed me to use multiple domains with one installation of WordPress (I don’t like sub-folder blogs or sub-domains sites). This client project, if we go forward, will be a similar setup – multiple single-domain blogs hosted on a single WordPress installation.

So what steps should I follow to

1. Set up Multisite​ – I know how to install it, but how should I configure it considering I want to use it for separate domains, not sub-folders or sub-domains?
2. Move content – I assume the regular WP export-import process will work?
3. Map the domains to their new home on the new installation?

To map your domains, you can consider to use the WordPress MU Domain Mapping plugin which works with wordpress 3.0 as well.

Otto has a tutorial online: WordPress 3.0: Multisite Domain Mapping Tutorial

Next to that Import/Export should mainly do the job to transfer the sites.