If i summise correctly, the saame reason you cant netboot a 68k mac 
is the reason why you cant boot right into bsd. I have been told that 
in non OF (open firmware) macs expect the boot device to be an HFS 
volume (same reason why you cant boot an hfs+ volume on older macs) 
the rom just wont let it. However, i have herad of  one rumor about a 
netbooting machine with some crazy test version of appleshare. But i 
dont have enough details for it to matter.

>Hi All,
>  Is it possible (and documented) to diskless boot a Mac (68K series) into
>an XTerminal (ie: thin client)...
>
>thanks in advance,
>
>   john