I am trying to build a root Slackware 15.0 file system, for a system that is not readily accessible, and sports a 14 year old motherboard, not capable of UEFI boots.

So I am working on a system that has a UEFI bios, but is run in legacy mode. For some reason booting off the Slackware DVD ends up using grub, which I don't really want.

I would like to revert back to a straight LILO based boot on old system, and am trying to do so by creating a new system (legacy) disk on an office Slackware system, with the disc drives disconnected, and only the SSD for the target system, and a CDROM drive. Any guidance on how to disable the grub boot would be appreciated. The MB is a Gigabyte G77 board, on the creating machine.

I did allot of reading but did not identify the solution to this issue, and am looking for some additional guidance.

@linuxbird, from your OP question, if I undersand correctly :
create a slackware-15.0 LILO booting Drive FOR an old legacy (CMS) system,
this booting Drive (below 'Target') being created on a more recent
UEFI computer (below 'CreatingPC') booted by
slackware-15.0 install DVD (or USB...).

Slackware-15.0 install DVD (or USB...) setup command will
will propose LILO (legacy) boot install to Target, *if* DVD booted legacy (aka CSM),
as for example documented in slackware64-15.0/README_UEFI.TXT, example from
a (slackware mirror) .../slackware/slackware64-15.0/README_UEFI.TXT
Is also in root fs of Installation Drive.

From this slackware-15.0 README_UEFI.TXT I deduce:
if install DVD booted UEFI, or UEFI partition detected, Setup proposes ELILO
to install on target drive;
IF legacy booted (and NO UEFI partition?), Setup proposes LILO
to install on target drive.

So a way to set boot by LILO from slackware-15.0 Setup is:
boot slackware-15.0 Install drive by
CreatingPC BIOS Setup boot Legacy (or CMS) boot, NOT UEFI boot,
not always easy to find.
Or bypass Setup install boot part, ..., and install lilo yourself (lilo.conf, run lilo command, etc...)

Some PCs, as my old Lenovo ThinkPad T520, cannot boot from Drive partitioned GPT,
boot drive must partioned MBR (DOS);
even if its (buggy?) UEFI/BIOS recognize GPT partitioned drives
that can be mounted and worked with.

An aside:
possibly better install a huge kernel, instead of a (generic kernel + initrd),
in case of a Drive created on one PC to run a system on another PC?
OR a (generic kernel + an initrd with all 'modules' of a huge kernel,
is equivalent to a huge kernel?
I am not sure of it.

Umm... good lock; can be touchy, and my deductions subject to modifs!
--
Jean-Pierre de ProtozoWare

The dvd may boot using grub and in uefi mode, however setup will give option to install lilo. Make sure the drive is dos and not gpt. On some old legacy systems the partition boot flag needs to be set.