Yes, Wine is open source. You'll probably want "Wine Staging". https://dl.winehq.org/wine-builds/macosx/download.html. You'll also need XQuartz installed. https://www.xquartz.org/. I have the 1.12.1 OSX client, but I prefer to run the Windows client as it's more stable. There also isn't a working OSX client for Burning Crusade servers (2.4.3), so the Windows client is the only option.