It would be much more convenient to track particular bug using rss feed then currently using tracking of new posts by e-mail ("cc" feature for particular bug)
Per bug RSS feeds are not really doable. The idea is even kinda funny.
But if you really want some method of tracking.
Use the xml feeds. http://bugs.gentoo.org/show_bug.cgi?id=118675&ctype=xml
unfortunately this doesn't work with akregator-3.5.0
Perhaps I am missing something here. If you do a search for bugs, on the buglist page, there is an "RSS" link at the bottom to which one can subscribe to RSS feeds of bug searches.
You want a particular bug? Doubtful, since I am neither an RSS maven nor someone who wants to do wholesale hacks into bugzilla that should really be done upstream.