For World of Warcraft CD Installations only (non-DVD):
If you are installing World of Warcraft using the Crossover Install Software list you shouldn't need to worry about this. However, if you run into problems installing from CD (such as the installer reporting of duplicate filenames) try the following.
Mount the WoW CDs (or images if you made .iso's) without the unhide option sudo mount /dev/cdrom /mnt/cdrom -o uid=1000,ro,user
Instead of the crossover default of: sudo mount /dev/cdrom /mnt/cdrom -o uid=1000,ro,user,unhide
You can also try creating a folder on your desktop and copying all the files from the WoW install discs into that folder. When you install WoW with Crossover Games expand the section Choose Installer and manually select the install.exe in the desktop folder.