I have installed Protocase Designer on Linux (Ubuntu 9) using Wine. The installation appeared to work perfectly. There were 2 hitches however:
Silkscreens can't display
You can still export a silkscreen template, modify it, and submit it with your order
Estimation/ Ordering doesn't work
You can email your case file to our sales for a quote
We can also recommend using Sun VirtualBox (free) to install windows (not free) in a virtual machine on your linux machine. Then the ordering does work.
We are currently working on the next major version. It will be a re-write and will be available for Windows, Mac, and Linux.