I did that in 2012 for a pet project with a friend https://github.com/SnippyHolloW/HN_stats

Here is the trained topic model (Nov. 30, 2012) with only 40 topics (for file-size mainly) https://dl.dropboxusercontent.com/u/14035465/hn40_lemmatized...

You can load it with Python:

  from gensim.models import ldamodel
  lda = ldamodel.LdaModel.load("hn40_lemmatized.ldamodel")
  lda.alpha = [lda.alpha for _ in range(40)]  # because there was a change since 2012
  lda.show_topics()

Now if you can figure out what is this file: https://dl.dropboxusercontent.com/u/14035465/pg40.params I'll pay you a beer next time you're in Paris or I'm in the Valley. ;-)