Here's a quick and dirty guide to setting up SheepShaver on Ubuntu that I've written:
http://www.emaculation.com/doku.php/ubuntu
it includes a couple of SheepShaver packages that can easily be installed in Ubuntu, as well as a brand new build of the emulator which is not recommended, but which could be improved if some people test it out.
There are a few linux-specific tips for the emulator and a basic walk-through for the GUI. It should be enough to get new users up and running.
