I tested HG/SS's RNG yesterday. As far as I can tell, it seeds identically to D/P/Pt (with lower delay, due to the faster title sequence). Wild Pokémon still use method 1 (or more probably J). I haven't checked whether egg PIDs use a different RNG yet.
However, with no journal or Pokétch, we'll have to find other ways to advance the RNG and check if we hit the right seed.
has hg/ss rng been cracked?