The man pages on 'mount' and 'fstab' provide all the details but the following should help you:
The CDROM should be in the group 'cdrom'. If the user(s) in question are also in that group, they have access to the device.
In /etc/fstab on the line for the device in question, add the flag 'user' or 'users' to the mount option. User keeps the drive under ownership of the user who mounted it, while users allows any user to umount it regardless who mounted it.
Alternately, the option 'umask=077' or 'umask=000' should allow users to mount/umount the drive.
Here's a line from my etc/fstab file:
/dev/hdb /media/cdrom udf,iso9660 defaults,noauto,user 0 0
Best of luck, I hope this clarifies it some. Do read the man pages though, there's a lot of stuff in there.