It’s a breeze! Well, almost. Following the build instructions inside the “docs” folder of the source (download at https://www.advancemame.it/.) worked fine to give me an install.
(Don’t forget to run
advcfg, the video configuration utility, first, I had “no video device found” until I had run it),
on my 4K monitor, though. it only displayed in the upper left, at about 1024×768. Long story short, the fix for that was to run
sudo raspi-config, and go to “Advanced Options”, “GL Driver”, and disable that experimental GL driver. Now I get fullscreen, with no other changes.
Comment with any problems of your own attempting this!