It was my understanding that ide-scsi was no longer needed in kernel 2.6
(which I run). You replace ide-scsi with ide-cd, because kernel 2.6 can
write to the ide interface now directly.
I've compiled serveral 2.6 kernels and removed scsi emulation and the
entire scsi portion of the kernel, and having previously used ide-scsi
as a parameter at boot before can vouch for it functioning correctly.
YMMV
Alex