Downloaded plscsi.tar.gz and tried..

sudo plsci -w output
export PLSCSI=/dev/sg0 // B PLEXTOR CD-R PREMIMUM 1.02
export PLSCSI=/dev/sg1 // @ IOMEGA ZIP 100 03.H

sudo plscsi /dev/sda output
// sgioOpen.Open: No such device or address
// plscsi.sclOpenNext: "/dev/sda" not opened
// -x001 = -1 = plscsi.main exit int

similar output for sudo plscsi /dev/sd[bcd]

Will upgrading to other kernel-vesion work?

-ishwar