At one point back in the day it wasnt possible to use any drive, you had to use one of the Amiga specific.
I had a Zappo CD-ROM for a short time, it was interesting to browse Aminet CDs (Aminet was bigger than the Internet at one point
) and magazine cover CDs were good as you got a LOT of software.
But for the most part I didnt see the point as they were slow (1x or 2x speed) and CD32 games weren't worth buying over their Amiga equivelents (generally speaking, CD32 owners may disagree!).
These days, a quick google reveals you can either use SCSI via the trapdoor or a buffered IDE to connect CD-ROMs. Instructions are vague though, I have no idea how to do it sorry.