Hi,
the script in the squeakland deb package (http://squeakland.org/installers/ux/debian/) does something like this with the squeakland plugin image and the .npsqueak/ dir.
there were no such a script in the deb file (there is a link in usr/bin/squeakland but it does not point to any file). I found a npsqueakrun script in google which does the thing I would like for ubuntu.
Thanks