Okay, I swapped the 266 for a 233, and got it successfully installed.
I've run installboot to make the disk bootable.  However, I'm not sure
what boot command I need to use to make it boot.  It's installed on
/dev/wd0, which I assume is an IDE disk.  My available devices appear to
be:

ide0	/pci/mac-io/ide@20000
ide	/pci/mac-io/ide@20000
ata-int	/pci/mac-io/ide@20000
ide1	/pci/mac-io/ide@21000

But I'm not sure how this is supposed to translate into a boot command.
I've tried:

     boot ata/ata-disk@0:0

...but the system then appears to try a Mac firmware boot (mouse pointer
appears, and flashing disk appears).

Can anybody suggest a boot command for me?  Much appreciated.

Thanks,

-Bill

-- 
 William R. Dickson -- Consuming the Earth's limited resources since 1968
 wrd@awenet.com   < >   http://www.awenet.com/~wrd/   < >   ICQ: 14117523

     Religion is regarded by the common people as true, by the wise as 
     false, and by the rulers as useful.
                                          - Seneca the Younger
					    (4?B. - 65AD)