>I have an old 4x SCSI CD drive kicking around my room and I want to 
>use it for something. My LCIII is the only machine with SCSI but 
>it's not an Apple drive - is there any chance it will work?

Yes, it is quite likely that it *will* work.  (Not
all systems are as brain damaged as Apple when it
comes to recognizing CD-ROMs!  :>  Though Sun comes
pretty close...)

You can either plug it in and boot the system
(i.e. assuming the system is *off* so your 
fiddling with the connection doesn't perturb 
the SCSI bus) *or*, if you are adventurous :>,
plug it in while the system is running (though
hopefully largely quiescent!) and do a
    scsictl scsibus rescan all all
(check the man page for details, I may have
misremembered the exact syntax).

Insert a CD and mount(1) it...

I usually have an entry in fstab(5) like
    /dev/cd0a    /cdrom    cd9660    ro,noauto    0    0
which will allow me to quickly mount it using
    mount /cdrom
(note that I have already `mkdir /cdrom`)

Don't forget to umount(1) it when you are done
(I don't think you will be able to eject the CD
unless you do so...)

Note, also, that you will need to terminate the SCSI 
bus (assuming this is the first time you have added
an external device to the bus).  Some drives have
built-in terminators; some have terminators that
you can turn on via a DIP switch; others you have to
add your own termination...>

Also, be sure you know what type of filesystem
is on the disk -- i.e. this fstab(5) example assumes
iso9660 (by far the most common?).  Trying to mount
a CD with an A/UX filesystem this way will lose, lose...

--don