If you have a look to this file
(
http://www.viaarena.com/Driver/via%20linux%20unichrome%20kernel%20driver%20source%20code%20installation%20guide%20v0%5B1%5D.83.gz)
you'll find all the steps that I followed to have drivers compiled and installed.
This is just a brief resume of the steps required to setup your environment:
All these steps are listed in the pdf guide I pointed you to at the beginning of this post, maybe not in very deep details, but they are there.
Then you have to follow the compiling instruction related to ubuntu 7.0.4 contained in the pdf guide .
Once all the compiling process is completed you'll find in the root of your box a directory called
CLE266CN400CN-CX700CN800XORG40072
In this directory you'll find the newly compiled drivers, utility and install script (vinstall)
Launch this file, select your CPU, then select option "2", and you're done.
It is definitely not a one-click "forward-forward-forward-finish" process and some linux skill is required to get successfully to the end.
Have a try with this and if you still find yourself in troubles let me know.
HTH
Marco