As some Mac users may have already noticed, installing Feisty Fawn on the Mac using Paralles isn’t easy. But there’s a way to do it:
To give credit where credit is due, you can find an excellent tutorial here.
Use “Custom options” when creating the Virtual Machine. Chose “Solaris/Other Solaris” as operating system, disable Sound and USB. When Ubuntu starts give live vga=790 as startup command. This should get you started, for the rest I suggest you read the turorial.