At the risk of looking dumb:
cd /usr/src/sys/arch/macppc/conf
config GENERIC
has started reporting:
> config: cannot read ../../../../arch/macppc/conf/Makefile.macppc: No such
file or directory
> *** Stop.
(1.5.2 userland)
config(8) is tied to the kernel. you probably want to build a new one
of those first...