Xfire has a limit of 1000 people on the stream, so you'll have to get there early if you want to watch it. My guess is that 1000 streams is quite inadequate. Based on numbers that I've gotten on the YouTube video's I've posted here, they could easily have ten times that and still be short. Hopefully there'll be more of this, and the number of available streams will increase.
Nihilum's raid will take place at 19:00 CEST April 30th, which is 12:00 p.m. CDT, 1:00 p.m. EDT, and 10:00 a.m. PDT (all on April 30th, no crossing of the international date line).
Mark your calendars for this one. I know I will be!