It's really starting to seem like that this crossover will be just a couple of shorts that won't get in the way of the episodes. The magazines have seemingly kept the old episode positions up until now, so I'm starting to really doubt that this crossover will be taking over the show for two weeks like initially reported.
Too bad I'm at work right now, so I couldn't check the first part of the crossover live. It seems like no one else here did either... Checking the Tv Asahi site, it seems like today's episode of Shin-Chan is a movie special, airing from 19:00 to 20:54, taking up almost two entire hours.
Edit:
Checking the preview clip in the official site, it seems to be unrelated to the Fourze crossover.
http://www.tv-asahi.co.jp/shinchan/ It really seems more and more likely that this "crossover" is probably going to be just some short segment, rather than something taking over both shows for two weeks.