I hope I'm not posting anything notoriously known to Mac users, but the search keeps quiet, so I'll give it a shot 
For those who use Mac OS X and want to use Mp3tag as well, here is the solution, which perfectly works for me (Mac OS X 10.6 Snow Leopard on MacBook Pro):
- download and install WineBottler (http://winebottler.kronenberg.org/).
- download Mp3tag installer (I use version 2.45a as I write this)
- install and run WineBottler.
- in WineBottler, create a new Prefix and select Mp3tag installer for it. No other configuration is necessary, however you may want to read through WineBottler documentation on its website.
- follow installation procedure - in the end, Mp3tag app should be ready for you wherever you've saved it (typically in Applications)
- run Mp3tag.app and you're done!
There are certain limitations, such as non-functional drag'n'drop, several keyboard shortcuts (like shift+arrows), and maybe others, but it's acceptable for me...
If you have your mp3s on a shared network drive, like me, you might want to know, that you can find the network drive under This computer >> Z:/Volumes/[shared volume name].
Feel free to precise this information with your own experience. And of course, enjoy Mp3tag under Mac OS X 