OK thanks! Got the CD0 file in Devs -> DosDrivers, used Information to change the Unit# in CD0 to match the SCSI device ID. I'm a little unclear on checking for the presence of L:CDFilesystem. Where does/should that reside?
L: is a logical directory (an 'Assign' in Amiga parlance) equivalent to SYS:L (and SYS: is a logical directory equivalent to your boot partition). So if you open a shell and type 'dir L:' (without the quotes) you should see CDFilesystem and a few other files.
You can also open your boot partition in Workbench and select Window->Show->All Files. L should then appear in that window and you can look inside. System files and directories are hidden by default - they don't have icons. Icons are those .info files you'll see in most dir listings in the shell and file requesters.
EDIT: Whoops, you all beat me to it while I was typing.

Hope the UI tips come in handy, rcgrabbag.