Well, you can start off looking at the kernel howto at www.linuxdoc.org:
Alternatively, I plan on trying this out, and maybe some other folks do, too. I can send you a kernel compile in the next few days, and you can integrate it into the build kit.
Or, you might even be able to use someone else's image. My image is pretty tailored at this point, but it might work for you. I'll let you know when I've got a new one.