Booting -current on the z50

Hi --

I'm hot to use -current to try the audio changes which Elijah
mentioned on this list recently. I installed . .
./NetBSD-daily/HEAD/200809250002Z/hpcmips/binary/sets/kern-GENERIC.tgz,
base.tgz, and etc.tgz to a compact flash card.  The install went
swimmingly. Using the hpcboot.exe which was supplied with the same
build, I can boot the install kernel, run sh and

# mount /dev/wd0a /mnt
# cd /mnt
# /usr/sbin/chroot /mnt

and then I can use the binaries on the cf card. But, when I set the
hpcboot parameters as / and netbsd instead of \Storage Card\ and
netbsd.gz, I get:

[. . .]
boot device: <unknown>
root device:

What's the incantation to get the boot to finish?

Thanks!

Tom