Nobody knows exactly, except it involves having some custom arragement between NI and UK, and keeping NI inside EU custom area.
Actually this was predictable since the begining, to have the Good Friday agreement in place there is no other way.
I did not read it, i don't need to, becouse I know how EU works and their position it was clear from day 1, and I can bet my landcruiser against a 20 yealr old bicycle that basically BoJo got the same deal as Theresa May, worded maybe a bit different, so he can show that he actually did something ( not ) and to be able to sell it to the nuts in Parliament.. ( it doesn't look like it will happen ) .
This will drag on for years.. this people have no clue what are they getting themselves in for.
As much as I would like for this saga to end, it will not happen.