OK, this seems to work for Slashdot, it just takes an hour and a half on my PC...
Code:
class AdvancedUserRecipe1230335014(BasicNewsRecipe):
title = u'Slashdot'
oldest_article = 7
max_articles_per_feed = 100
feeds = [(u'Slashdot', u'http://rss.slashdot.org/Slashdot/slashdot')]
def get_article_url(self, article):
return article.get('feedburner_origlink', None)
EDIT: The second run of this took a shade under 2 hours. Again, it does work, just VERY slowly. I dunno if it's my PC or the website or what, but I will note it occasionally cuts the ends off comments. Might be the site.