After some trial and error, and some help from Paul G, I managed to build Open Einstein for both my Intel Mac and for my Nokia 770, using just my Macbook. I followed the directions to build at the Google Code site. I'll have more explicit directions soon, but the code does build and run on the 770. And you don't need scratchbox to build it! Excellent work Paul.
Here are some screen shots (click for bigger versions):
After Einstein was built, the directions for starting it are the same as before. The easiest way to control einstein is via SSH into the 770, so that you can shutdown all the Hildon interfaces.
Full directions to build this will be up soon.
Update: There is a new Einstein Platform 2007.7 User Manual at Paul's Einstein Page.