Have a look here:
http://wiki.netbsd.se/index.php/How_to_build_NetBSD-current

2006/10/16, Avram Cristian <cavram@gmail.com>:
> I tried yesterday to compile current on a 3.01  x86 box using the guides at
> http://www.netbsd.org/guide/en/chap-build.html.
> So, I installed 3.01, then downloaded the current src packages from
> netbsd.org and after that i updated the sources using cvs.
> It fails at building tools. I was wondering, is this the right way to get to
> current? Maybe that guide is outdated?
> What steps are you guys using when compiling NetBSD-current?
>
> Thank you!
>