Porting Guide

Okay, so this might be a dumb question, but here goes. I am currently porting NetBSD to an embedded ARM board. NetBSD always touts itself as being "the worlds most portable operating system", but I've never seen any actual documentation on porting it. Am I just not looking in the right places? Is there a porting guide or something similar? I know that <ugh> linux has some documentation which tells you where to do things like boardlevel initialization, etc.. Where is NetBSDs? I have brought OpenBSD up on several unsupported x86 boards, and am familiar with how the *BSDs in general work, but I have several other engineers working with me who come from a Linux background and I'm having trouble keeping them onboard with this project.