I'm writing to address the issue of where the NSI installer scripts went. Sorry for taking so long to get to this, but as I'm sure you'll understand, it's extremely busy trying to help run a commercial enterprise.
We have decided to discontinue distributing the NSI installer scripts because we needed to discourage parties from exploiting the ease of creating new distributions in a way that goes against the spirit of why we made the project available under open source in the first place. We realize that it's not possible to entirely prevent such misuses, but we want to at least signal our intentions by making it harder to do so.
The original NSI installer scripts would have been made available on the archive SVN repository, which we made accessible for a period of 3 months after we migrated to Mercurial. At this point in time, it is retired and no longer available to the public.
We regret that this may have inconvenienced you, but we felt this move was in our best interest.
Good luck in your future development endeavours!