I’ve just installed a lovely new plug-in that makes it possible to append your comments not just to the bottom of a post, but to the particular paragraph that you’re interested in discussing. To do this, just hover over the paragraph in question, and look for the little “talk” box, like so:
(If someone has already left a comment on that paragraph, the box will contain a number instead.) Just click on the box, and add your comment — it’s as simple as that!
Please let me know if there are any difficulties with this, or if it turns out not to be that useful.