Open up one of the BBS links, such as this one:
→
http://jbbs.livedoor.jp/computer/313...200937754.html
Scroll through the numbered posts, such as post 9 from the previous link:
Links are usually posted in pairs, where the first link shows you the DVD cover. The second link takes you to a file host site where you can download the .torrent file. You then take the .torrent file and open it up in your bittorrent client, and download as you would a normal torrent.
Sometimes one post has more than one link to a filehost--they just rehost the same .torrent file in case you can't connect to one of the filehosts.
If you're used to just browsing the torrents subforums here at AO, rest assured that almost everything that gets posted on a BBS shows up here (and actually, more, since people here also post their finds on Share, etc).