WordPress MU

So I already have a standard WordPress blog and I want to implement WPMU into it. Is this possible, or would I have to restart from scratch?

If it IS possible, how easy is it? Is there some documentation I can peruse?

Thanks.

Import your existing blog into the WPMU setup.

Is there any documentation for this?

Thanks.

via SQL
http://bavatuesdays.com/importing-a-single-wp-blog-to-a-wpmu-installation/
OR, via XML
export XML from single WP install. Then in WPMU, create a blog or import to existing blog WXR.

Of course, make SQL backups of both WP and WPMU installs for good measure before the attempt :-)