If you try to specify an ISO image to be attached to a vm, in the open dialog any Alias entries are grayed out.
If SymLink (via Terminal.app) entries are established/substituted, such entries in the open dialog are supported - not grayed out.
For assisting with creating SymLinks,
1) http://hints.macworld.com/article.php?s ... 0610290643 (brief tutorial)
2) http://seiryu.home.comcast.net/~seiryu/ ... inker.html (automator) and others (Google: symbolic link)
Edited: add links