For everything on the initial announcement, see our last post, which also has the sizable voice actor list.
As for viewing it, here’s the details:
Nico Stream Link
June 29 at 7:00 a.m. in Japan – that’s June 28th, 3:00 PM PST – 6:00 PM EST
Of course, it’ll be in Japanese. Don’t expect subtitles either.
There are two issues here: 1) You need to have a Nico account (relatively simple), and 2) You need to be able to bypass the region lock. The latter is a bit more complicated, and as there are various methods with different requirements I cannot recommend one in particular – you’ll need to figure that out on your own.
That said, this will probably be available in some other form sooner or later, so it’s just as well to wait. Stay tuned here for updates in that department.