Oooh, I do keep harping on, don't I...

This site has details on how to create a CDR which the Dreamcast will boot,
as well as instructions on how to build a PC->DC serial cable, and a 
serial upload slave CDR for uploading code from the PC to the DC.

http://marcus.mangakai.org/dc/

Everything someone cleverer than myself might need to get NetBSD running
on a DC, with serial I/O ...

There's nothing there that needs Windows, either :)

-- 
-------------------------------------------------------------------------------
        Ooh, it's 'orrible being in love when you're eight and a half.
        I've got your picture on my wall and your name upon my scarf.
-------------------------------------------------------------------------------