Josh Tolbert <hemi at puresimplicity dot net> recently put together a lot of stuff related to the NetBSD/dreamcast port and created an easy to install NetBSD Dreamcast system along with a short introduction on how to setup your Dreamcast and what need to be done to increase the usuability of the NetBSD/dreamcast port (for now, focus on wscons(4) support for the Dreamcast framebuffer and getting POSIX threads to work). Josh's How-To and all stuff needed to get NetBSD working on your Dreamcast can found here.