Even for logged in posting you do not need a dreamwidth account. You can simply log in with OPEN ID. To do so, have livejournal and dreamwidth open and be logged into your livejournal account. Ony dreamwidth select "log in with Open ID" and it will ask you for your livejournal address. username.livejournal.com
Livejournal will then quickly come up with a page where you confirm that the journal you're accessing is yours. This feature does not give dreamwidth access to your livejournal account.
IMPORTANT: If your comment, request or fill does not show up on the dreamwidth comm you will have posted it after the data was transferred from livejournal. In this case, please repost it on dreamwidth. I am sorry for the inconvenience.
NOTE: Today on 13/01/2012 I have not yet had time to update the links on the dreamwidth comm's meme entries. Therefore they will still lead to livejournal. Sorry abot that and I'll fix is asap.
The lj meme posts have now been closed. Please move to the dw ones.</center