I can see where to get an rss feed for the BUG LIST, however I would like to get rss updates for modifications to current bugs if possible.
What you're asking for is the subject of this enhancement bug:
https://bugzilla.mozilla.org/show_bug.cgi?id=256718
but no one seems to be working on it.
My first guess is that the way to do it is to add a template somewhere like template/en/default/bug/show.atom.tmpl with whatever you need. Put it in custom or an extension as needed.
If you're interested in working on it or helping someone with it, visit channel #mozwebtools on irc.mozilla.org.