For what it's worth, I would say that the path to third is about seeing the "sameness" in every perception, including self, and that sameness is "emptiness".
There are two aspecits of this path:
1) concentration/jhanas seriously kick in, if you are wired this way. All the jhanas and formless realms are at least touched on if not dwelled in. This is (nearly) endlessly fascinating.
2) conventional perception, including the nanas, is really seen to be constructed from basic building blocks. As a result, there is a lot more freedom in life.
The mature side of third comes with the depressing realization that the jhanas and the new freedoms are just even more whiz-bang experiences -- which if you are wise, you'll see as more evidence of the same emptiness of perception.
When all of these perceptions/insights are really established, you can go through nana cycles as if it is running in the background. You'll probably have lots of fruitions. But one of nanas cycles will go deep enough (or really, it might be better to say, they will become so shallow as to be insignificant) and a third path fruition will occur. It will have the same sense of completion as the previous two paths.
Just because all of this begs the question --- fourth path is very similar, except the concepts/perception of an indepent/observing self and enlightenment are seen through completely. This is really subtle stuff and indeed relates to a very basic sense of "pride".
Hope this helps!
Adding on: as far as practice goes, at this point mindfulness is probably a default state and noting/noticing happens fairly automatically. So practice can really do itself. All that has to be balanced is alertness and relaxation, the mind does its thing. The mind will go into concentration states and will instinctually investigate things that seem like ill will/hindrances. So it's mostly "getting out of your own way"

Anything that seems like a road block should be investigated to find its inherent emptiness, concentration states should be enjoyed and dwelled in to condition the mind. It's a facinating path so enjoy!