So, I downloaded PASSION and PASSION-DEMOS from Kikito's GitHub repositories. As supposed to copying PASSION three times, I created symbolic links in each game to the PASSION Git checkout. This should have theoretically worked, however:
LOVE doesn't love symbolic links.
LOVE doesn't seem to be able to follow symbolic links, leading to the problem that LOVE says that passion/init.lua doesn't exist, even though there is a symbolic link to it.
This problem would probably effect all Unix-based operating systems, including Linux, Mac OS X, and the BSDs.