Right, so I'll update this & it'll use the 32-bit stable version.
I'm not sure what you mean about this
I mean it'll download the latest version, regardless of number.
OK, so I've set App\AppInfo\installer.ini to download this...
[DownloadFiles] DownloadURL=http://www.mutools.com/mulab/mulab-win.zip
As you can see, there's no version number in that filename and it always contains the latest one. This is done by MuLab & is nothing to do with the PA installer. So when MuLab updates, you can just run the installer again & get the current release. The downside to this is that, if there are any major structural/operational changes between releases, the launcher won't know how to deal with them but I've judged that this is unlikely to happen, going on past form.
I'd like to adapt it for personal use to update the betas
Yes, that's possible, no programming knowledge required, but you'll have to change the line in installer.ini to the correct link as the filename for each beta version contains it's number ie: mulab-6-4-14-win32-exe.zip, rather than "mulab-latest-beta-win32-exe.zip" (for instance). Does that make sense? Then you'll have to recompile the installer. I'm happy to take you through this step by step if you want.
But... looking at those betas, the download only contains two files so it's just a case of replacing App\MuLab\MuLab.exe & Data\MuLab.ID. Very simple to do manually but if you wanted an installer to do it for you I would say it would be easier to create a separate plugin installer that you could just run over the main app. But you would still have to edit & recompile it for every release because of the filenaming issues above. If you want to do this & get into the ins & outs of launchers & installers just say so & we can do it.
By the way, did you ever find out what MuLab.ID was for? Does it contain registration data?