ies4osx is a great project for getting various versions of Internet Explorer up and running on your Mac, facilitating testing for web designers and developers working with a Mac.
If you’re still running 10.4 Tiger like me, you may need to jump through an extra hoop to get it running, namely downloading a Tiger-specific version of Darwine.
Once I did that, things ran pretty smoothly, and IE6 on Mac seems to do a pretty good job of approximating behaviour of IE6 on Windows. One things I have noticed, however, is that IE6 running on my Mac won’t apply a common PNG transparency fix.
Conditional comments work fine, but the iepngfix.htc CSS behaviour doesn’t.