Go to the dreamwidth.org, look for the log in box at the top right corner. You should see the 'log in with an Open ID' link right next to the username box. Click on it, then use your lj address in the box (that would be tkp.livejournal.com), lj will ask you to verify, and after that, voila, an account.

Take a moment to verify the e-mail address once you have that account, without that you won't take part in the lottery (and the lottery picked me four days after I set up the Open ID account, so it works fine :D)