[netbsd4.0.1]how to re-compile netbsd kernel

[wang_jiabo <jiabwang%redhat.com@localhost>]

Hi, all:
could you tell me how to re-compile netbsd kernel.
I downloaded syssrc.tgz,sys.tar.gz,config.tar.gz,
and untar all the files.
but couldnot do  "config <mykernel>",

thanks everyone
regards
jiabo