Some further progress since this time yesterday...

With some prodding from the eminent Mr. Simpson (thanks!), I was able 
to boot the system from floppy and get through partitioning the disk in 
sysinst; sysinst, however, seemed a bit cranky and coredumped during 
set installation. I untarred the remaining packages by hand and ran 
MAKEDEV and installboot (familiar with this from years of having to do 
it on sparc). Theoretically I should now have a complete installed 
system with root at wd0a.

My understanding is I should be able to boot it with:
0 > boot hd:0,\boot netbsd

Of course, though - this doesn't work. It exhibits the same behavior as 
yesterday -- goes to the "I'm trying to boot MacOS" grey screen.

It would seem, generally speaking, that this system does not want to 
boot from an IDE device, be it CD-ROM or internal disk.

Any further input would be much appreciated!

dp