Tom, You didn't mention which hardware you are working with, but there is a good guide at powermaclinux.net: http://www.powermaclinux.net/plain_page.php?46
The first paragraph says that it is for iMacs but that the steps should be nearly the same for all newer Macs. Hope that is helpful. Darren Addy Web Specialist Information Technology Services University of Nebraska at Kearney
