Aha, last ditch effort on a little googling turned up this example, scroll down to the bottom. Apparently a setup() function in conf.py will get called with the app. I was able to define the following at the bottom of my conf.py:
def maybe_skip_member(app, what, name, obj, skip, options):
print app, what, name, obj, skip, options
return True
def setup(app):
app.connect('autodoc-skip-member', maybe_skip_member)
Which is obviously useless (it skips everything), but that’s the minimal example I was looking for and couldn’t find…