If you search the archives of this list (this had to be a couple years 
ago) you'll find an email I wrote detailing the process.  It describes 
booting a Powerbook G3 Series 266mhz machine from the internal hard 
drive.  NetBSD ran beautifully on the powerbook (OF 2.01) for a couple 
years.  Recently I reinstalled a newer version (1.6 iirc) and that went 
off without a hitch too.  I found the Install guide to be very 
valuable, clear and complete.
IIRC, I had to setenv boot-device, setenv boot-file setenv real-base 
and setenv load-base.  That was it.  And it worked with and without the 
System disk nvram patches.

I wish I knew all the variables off the top of my head.

HTH

Jeff