I was digging around in the source tree trying to find the installer project for the tools. Turns out it uses WiX, something I have no experience with (I've used InstallShield, WISE, InnoSetup, NSIS, and .vdproj files).
WiX turned out to be pretty incomprehensible to me and the .wxs source files don't appear to be the same as the .wixproj files the current version of WiX expects to load in Visual Studio.
I found it easier to create a Multiverse Tools installer project for my own use using InnoSetup than to build the existing one. Is this something that the MV project would find useful -- as in, are there any pain points around installers right now and is what you have currently easy to maintain for whoever is maintaining it? I'd be happy to contribute my tools installer to the codebase if you want it. I can also post the resulting setup package somewhere so you can play around with it and see if it works well for you.
I also plan to make an installer for the client so I can build and deploy that from source. Same offer applies -- I'd be happy to contribute it if you found it useful. If not, it's still handy for my personal use.