Actually the way your going about it should work assuming the drives are rather current and your ide bios is also current.
The oakcdrom.sys device driver will handle more than one device by default.
If autoexec.bat =
A:\oakcdrom.sys /D:CD001 and
If config.sys =
A:\mscdex /L=G /V /D:CD001
then when oakcd driver starts you will see that there will be a reference to the device CD001 and number of drives = 2.
the mscdex (with the L switch) processes both drives and assigns drive G to unit 0 and drive H to unit 1. If you did not have the /L= switch then it gives 0 the first available drive number and 1 the next available drive number. The L was included only to clearly show in this example where each drive resides.
Now this example worked with a system (Dos 6.22 booting)where the CMOS drive parameters for the CD's were set at none but were detected by the ide interface controllers of the cd drives.
HTH and post comment if need more info.
I don't seem to be ableto find any specific switches for the oak driver - especially since it is no longer being supported and is kind of out in the public domain these days. However, you might find more if you look around some Linux type sites where switches are a way of life.