ajax update block on click to link
What have you already tried?
Having a look at the module JS, there is a function jquery_ajax_load_load(el, target, url). Have you tried calling it?

EDIT
To load block content you could either use another module specifically for it (search "drupal block ajax load") (ajax blocks) or you could create your own module that just returns block content when navigating to a url. This should be quite easy by implementing hook_menu and returning the value returned by block_load()