annotation/comment functionality?

I’m working on a project for a professor who wants to post a historical writer’s diary in a blog-like format. He wants users to be able to post annotations to selected portions of the text. For instance, if the post includes the name of a book or person, that might link to a page where people could add annotations, in a comment-like form. Presumably, annotation links for the same name appearing on different pages would link to just one page, similar to the way wikis generally work.

My first thought was a wiki plugin, but he doesn’t want users to be able to edit other’s annotations, only their own. The functionality we’re looking for is similar to that of the Pepys Diary (http://www.pepysdiary.com/), which I believe is done in Movable Type.

So, does anyone know of an easy method to pull this off using off-the-shelf plugins for WordPress? It seems like there might be a discussion board plugin might be made to work. Or will this require some custom coding?

Thanks!