CD-Roms can be a real annoyance to set up because the driver commands are so cryptic. Anyway, here's a brief description of what's involved.
In the config.sys file, you need a driver command line like this one from my computer:
Device=C:\cdrom\oakcdrom.sys /d:gem001
This line loads a device using a sys file in the c:\cdrom directory named oakcdrom.sys
The /d:gem001 is actually 2 different things. First the /d: tells the CD-Rom driver to load the name gem001. You see, one device driver can actually control more than 1 CD-Rom so each CD-Rom has to have a name so the driver can identify it. Here, my CD-Rom has been named gem001.
The second part is a command line in the c:\autoexec.bat file that looks like this:
c:\windows\command\mscdex /d:gem001
This loads a program named mscdex.exe which is in the c:windows\command directory. This program is told to control the CD-Rom that has a driver that calls it gem001.
In my computer, these are the two steps that setup CD-Rom use in DOS.
I hope this helps you a little.