Copying WoW installation from windows does work. You only need to create a folder in Ubuntu/other linux, and copy all wow files there.
After that, make sure that the file permissions on that folder are correct, ( CrossOver has permissions to read/write there) and that you have set your VGA drivers correctly (you have 3D support on). Linux distributions don't usually haveati/nvidia/amd drivers (3D that is) included by default.
As for the original poster, Creating symbolic links to a windows installation (eiter only on the directory, or a full "ghost installation" with symlinks) is something I have not tried myself, but with the knowledge that I have on Linux/CrossOver, I'd say that as long as the windows installation is on VFAT - partition you're good to go. on NTFS you might get it to work too, but you need to install 3rd party driver for RW support on NTFS (NTFS-3G for example), but since it's still gonna be a bit unstable I'd personally stay the hell outa that road....