Installing an unsigned application in /Applications (automagically) will probably be prevented by Apple's security mechanisms. ~/Applications will probably be easiest and cleanest, and I would also prefer ~/WUDSN instead of ~/jac - makes it easier to find ... If you provide Altirra as part of the package, I would put Alitrra in the directory structure parallel to WUDSN so that it's possible to re-use it for other purposes as well without having to find it somewhere in the directory structure below WUDSN. (JDownloader does this with unrar2 etc., so you might end up having it twice on your drive unnecessarily).
Anyway, thanks for the effort, I really appreciate this!