I installed Slack 8.0 on my old Thinkpad 560 with a pcmcia CD-Rom drive.
It was pretty easy. after loading the boot and root disks, at the prompt, it asks if you want to load the pcmcia drivers. put that disk in your floppy and type:
it will load the drivers and your CD-Rom will spring to life.
After that proceed with setup.
On my system it designated the CD-Rom as /dev/hdd
On a side note to this, I've been trying to install Slack 9.0 on the same system, but the pcmcia disk doesn seem to be working. It loads the drivers without any apparent errors, but when I run setup it can't locate the CD-Rom. I'm still trying to figure this one out.