HELP - ASUS Px9x79 P won't boot NetBSD-6.0

[newhouse%gandpline.com@localhost (Paul Newhouse)]

I have come into possession of an ASUS P9x79 P.  It has no PS/2 connections 
(which my older KVM switch uses) so I purchased a USB to PS/2 split cable.  
When I boot a DVD from the 6.0 boot.iso on the NetBSD site I see this behavior:

- when the "Boot in ... 5... 4.. ..." sequence appears I can hit enter and the 
count down ceases and the boot begins,

- it seems to discover a lot that I expect but, eventually says (something 
like) boot device: unknown.  It wants me to enter a device name BUT, it will 
not accept any keyboard input (I don't understand why it can't find the device 
on its own but, that's the next problem (maybe).)

Thinking the hardware might be misconfigured in some way I installed SL6.3.  It 
boots just fine.  Unfortunately I don't want SL on this system.  I was hoping 
to use it as a router and primary workstation at home.  Using SL means I have 
to figure out iptables which have always made me a little crazy (as opposed to 
ipf and NAT on NetBSD which also befuddle me at times but, I have them working 
to my satisfaction on the system I'm planning on replacing).

I'm thinking/hoping I just need to build a boot kernel with some options set so 
it will use the USB keyboard and mouse via PS/2. If someone would be kind 
enough to provide me with a few clues I'd appreciate it.

TIA,
Paul