technicly it already plays FLAC (i've been kinda a nerd when it comes to format) he kept the system basic enought to just respond to WMP, which is a bit bloted of a player (even more bloted with 10 and you got all those "music shopping" options) but because he uses that all you need to do is install the codec on the comp, and then boom you can play FLAC, the prob as he was saying is that his software isn't setup to except that format, not so much the format but the extension of the file (.flac right?).
now i haven't tried this but i've been around computer enough. try renaming the whole collection to .mp3 then redo your database (how ever thats done with this software or if you do in the WMP database). then once it's support just use that mass renamer to rename all the extensions to the .flac I found this trick out back when I wanted to listen to mp3s on the school computers, the admins don't like it cuzz most mp3s arn't legit. So to buy pass it we would call it .wav because we had permission to read .wav but not .mp3 thanks to WMP when it opens a file, it doesn't use the extension to determin what it is, it looks at the file it's self, so the system thought we were playing .wav and once WMP opened it, it just loaded mp3 like normal. So i figure the same thing would apply here, just rename it to .mp3 to get the system to see the files, and then WMP will use the right codec to play it when it comes down to it.
So someone try it and report back.