what is pckbc0 ? installing netbsd of HP DL140G3

I tried to install NetBSD 4 on a HP DL140 G3 today at work (and failed).
I want to use it as a firewall in front of a Linux server that has some rather sensitive stuff on it.
The DL140 G3 is the cheapest rack mount server that HP do and it comes with iLo and mine has a RAID
controller too, great stuff.

The install kernel hung for a long time and the keyboard didn't work.
According to this doc
http://maciejewski.org/?cat=8
if I recompile the kernel with pckbc0 support then it will work okay

so some questions...
What's pckbc0 ?
without pckbc0 is it just picking up keyboard input from the bios rather than directly from the
keyboard or something ?
How do I compile an install kernel without it and boot it ?
or can I some way to redirect to serial port and install from there ?
is there a better way ?
I think if I can get netbsd actually installed and running then I can then access it over ssh and
compile a custom kernel and use that, it's just the initial install that's defeating me

I'm using the standard NetBSD 4 ISO install CD

should I register failure to install on a HP DL140 G3 as a bug or something?

thanks for any help, Philip