(Replied to your comments on jmac.org, but until I get from-there email working...)

If you click the "Sign in" link under the leave-a-comment heading, you'll be taken to a screen where you can sign in through a variety of means, including via an existing LJ account. These didn't exist when I first set up the blog. Disregard my instructions to sign out first; I was confused as to you were leaving comments in the first place. :)