it's been a while but i think this is my mount file (placed in Devs/dosdrivers

----

/* $VER: CD0 40.6 (31.8.93)
 *
 * CD-ROM file system entry
 *
 * This file enables the CD-ROM file system which allows you to read standard
 * ISO-9660 CD-ROM disks from an Amiga with a SCSI or IDE controller.
 *
 * The "Unit" line defines the SCSI address of the CD-ROM drive. Drives
 * often come configured as unit 2, which is the default. Check the
 * documentation for your CD-ROM drive to find the exact SCSI address.
 * Note that most drives let you change this number using jumpers.
 */

FileSystem   = L:CDFileSystem
Flags      = 0
Surfaces   = 1
SectorsPerTrack   = 1
SectorSize   = 2048
Mask      = 0x7ffffffe
MaxTransfer   = 0x100000
Reserved   = 0
Interleave   = 0
LowCyl      = 0
HighCyl      = 0
Buffers      = 5
BufMemType   = 0
StackSize   = 1000
Priority   = 10
GlobVec      = -1
DosType      = 0x43443031

/* The Device and Unit fields are controlled by tooltypes in the CD0 icon.
 *
 * Device   = scsi.device
 * Unit      = 2
 */
---------------------

here's what is in the s/user-startup file:
(my system disk was called Asimov)
---------
;BEGIN AsimCDFS
echo "Mounting AsimCDFS..."
assign AsimCDFS: "Asimov:AsimCDFS"
assign AsimCDFS_Buffer: "Asimov:AsimCDFS_Buffer"
mount >NIL: CD0: from devs:MountList.CD0
;END AsimCDFS

------------------------

you can either have a mountlist in devs or a CD0 file in devs/dosdrivers

it really shouldn't matter.

there may be files in C:
i don't recall. I'd have to look in my emulation.
you Do need L:CDFileSystem
devs/asimcdfs.device
L/AsimCDFS

well, at least I think so.
I'll come back with more info (if i have it).