You might consider this this:
ftp://ftp.slackware.com/pub/slackwar...linux/sbootmgr
from README.TXT:
sbootmgr.dsk This nifty little tool allows selecting various devices to boot
from a menu, and even allows booting a CD-ROM in machines where
the BIOS doesn't support it (or it's supposed to support it, but
it just doesn't work). If you have trouble booting the
Slackware CD-ROM, you might try writing this image to a floppy,
booting it, and then selecting your CD-ROM drive as the boot
device.
If this fails, use your boot disk: bare.i
followed by the 2 root disks, found
here
that's hopefully all you need.