Here is how we do it
1. Make sure you have the latest Del.icio.us extension or add on (this is good practice)
2. Set up your linkage between your del.icio.us account and twitter. Log in to you del.icio.us account and go to Settings > Bookmarks > Bookmark sharing and work through the set up process. You will need your twitter ID and password.
3. Now save a bookmark using your Del.icio.us button. This will open the Save a bookmark window. You will see in the SEND field the @twitter recipient and underneath it the Message field. Type in your Message in this space.
Save the Bookmark and here is the end result published or shared in Twitter.
Extensions and Add ons for Del.icio.us - http://support.delicious.com/forum/index.php?CategoryID=11
Twitter – http://www.twitter.com
Del.icio.us – http://del.icio.us