First! (comment avatar)

Not a plugin question (WP3) but does anyone know how to select the avatar for the new site first comment? The comment is supposed to be from me -- my name and website -- but the avatar is a MonsterID.

The default avatar is MonsterID if the user does not have a local avatar or a Gravatar, so that is fine. I just can't figure out how to associate the first comment post to my (or other) account so that I can choose the avatar.