Hi, mdeange, and welcome to the Discussions!
Here's a
link to the MacBidouille dual-layer hack info, translated from French into English and posted at Hardmac.com. There's an download link for MBiDVD4ALLDVD.sit half way down the page. (It's obscure and perhaps should have been html coded with a colored link...) Click on it if you want to download it. Read the instructions carefully, particularly since you already installed Pachburn.
I don't know enough about region code flashing to answer your Region 0 questions. Perhaps someone more knowledgeable will join in. If not, here's a
link to rpc1.org to get you started for more info. Alternately, start a new topic with the question as the subject and someone will likely reply.
I hope this helps you some. Sorry I don't have more knowledge concerning this...
Gary