Many thanks to Bill, Colin and Jeff for their help on this.  Here is what
I have found:

I tried the SBC kernel (1.3_BETA) and couldn't make it through the boot 
sequence.

I then downloaded the newer how-to that Colin pointed me to and that
seemed to work (pretty much) using the NCRSCSI kernel (1.3_Alpha).


>> sd2 at scsibus0 targ 6 lun 0: <IOMEGA, ZIP 100, F.09> SCSI2 0/direct removable
>> sd2: drive offline
>> ^^^ This is with the zip ejected.  With the zip in, I get 96MB, 96cyl, 64heads,32sectors
>>    512 bytes/sec x 196608 sectors.
>
>Is the behavior affected by having the disk loaded or ejected?  I have had
>boot problems (hangs though, not panics) when the zip disk is loaded
>during the boot.  With the zip ejected, it boots fine and I can later
>mount the zip disk.  (This is a P550, Generic-45).
Doesn't seem to make a difference for me.


Jeff said:
>I happen to
>have a HDD that really cannot stomach the SBC driver.  I have found,
>however, that I can still use the zip, though I might add with
>considerable caution, using the ncrscsi driver.  I would suggest first
>assuring yourself that your HDD works properly with the SBC kernel, and
>once you are confident of that, start experimenting with the Zip.

I tried SBC, but couldn't boot.  The only problem I have now (after following
the newer how-to) is after I formatted/partitioned/disklabeled smoothly,
I ran 

fsck -f /dev/rsd2g

it ran fine, and gave me a prompt back but as soon as I started typing,
I got a kernel panic (trace gave lots of stuff).

so, I rebooted then continued on with tunefs, mounted the zip, 
and can read/write stuff fine.

Anyway, Jeff, what is the "considerable caution" you exercise?  I should
probably do the same.


Once again, thanks to everyone who helped.

Dan