The documentation for the BESX install is just okay.
Courtesy of fellow MVP Jason Miller the following training video provides _all_ of the required preparation steps and actual install steps that are required to install BESX on SBS 2008 or on a standalone server.
The above step-by-step helped us a lot in figuring out where things went sideways for us on our standalone BESX install.
We are still not all the way through reworking the BESX install as our client is in production. We will be working on the setup tomorrow.
Microsoft Small Business Specialists
Co-Author: SBS 2008 Blueprint Book