My hard drive is partitioned into three partitions - one being 700MB which I use as a "disk image" to make bootable Mac repair CDs. If you setup your icons in OS 9.x and then bootup into X (using another partition) the icons can be set to be DIFFERENT than when you're booted into OS 9.x!
This is quite cool because I now have two distinct looks. When I boot from the CD it looks one way, and when I am in OS X it looks completely different - including Finder window colors!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020305015742665