If you want to index just one page of a site, you can stick the full link, with query string and all, in the admin panel text box, set search depth to zero, links per to one, use no, and dig. If you want to restrict indexing to certain link characteristics, and you are familiar with regular expressions, check out
this thread. Maybe a new field in a table for certain link characteristics would be a good addition, but right now you'd have to edit the config file each time for different sites.