Most Lilo installations use a configuration file like the following one:
boot = /dev/hda # or your root partition
delay = 10 # delay, in tenth of a second (so you can interact)
vga = 0 # optional. Use "vga=1" to get 80x50
#linear # try "linear" in case of geometry problems.
image = /boot/vmlinux # your zImage file
root = /dev/hda1 # your root partition
label = Linux # or any fancy name
read-only # mount root read-only
other = /dev/hda4 # your dos partition, if any
table = /dev/hda # the current partition table
label = dos # or any non-fancy name
You can have multiple ``image'' and ``other'' sections if you want. It's not uncommon to have several kernel images configured in your lilo.conf, at least if you keep up to date with kernel development.
If you compile a ``zImage'' kernel and it is too big to fit in half a megabyte (this is common with new 2.1 kernels), you should build a ``big zImage'' instead: ``make bzImage''. To boot a big kernel image nothing special is needed, but you need version 18 or newer of Lilo. If your installation is older, you should upgrade your Lilo package.
Here I will give you an order of routines you have to do if you want to have both Linux and NT entries under Lilo menu:
First of all, I would suggest you to install a fresh copy of Windows NT 4.0 on your hard disk. I suppose that you already made a backup of your important data, so the NT installation shouldn't be a problem. During the NT installation, setup is not going to ask you where to place NT's boot loader, so it would be placed into the MBR (Master Boot Record) of your hard disk. But, there is a possibility for a previous content of the MBR to remain within the MBR (especially any previous Lilo), so I would suggest you (before installation of NT) to boot the computer with a DOS floppy diskette having DOS version of FDISK. At the prompt a:\ just enter the command: fdisk /mbr and restart the computer again (without that floppy).
After you have successfully installed your NT, you will see that it uses the whole hard disk or a specific partition of the hard disk (depending on what you decided during the setup process). So, it is advisable to 'shrink' the partition where NT resides in order to make some free space on the disk. Onto that free space you will install your Linux. After you have your NT configured and running, you have to boot your computer using a floppy diskette with Partition Magic utility by Power Quest. It is a graphical tool able to see all partitions on all hard disks you have. The best thing is that you can make some changes with your partitions but not to destroy your existing data. One of the available changes is to make your existing partition(s) smaller, so to get some free space on the disk(s) for other purposes. Although you are advised to make a backup before you make any changes to the partitions, I usually practice to 'shrink' NT's partition before I installed anything but NT itself (so, if needed, a repetitive re-installation wouldn't be a problem). Well, Partition Magic (or any other similar utility you are familiar with) will shrink your NT's partition (either NTFS or FAT) to a smaller measure and place it to either the beginning or to the end of the previous measure. It means that you may choose to have your 'shrinked' NT partition at the beginning or at the end of your disk (I usually choose NT to be at the beginning, so the ending part of the disk will become a 'free space'). After the 'shrinking' is finished, you may re-boot your NT in order to check the new situation: you may use Windows Explorer or Disk Administrator for that.
So far so good. Next step is to install your Linux. Case you are familiar with RedHat distribution (I hope with other distros is the same or similar), you start by putting your installation CD in the drive and re-boot the computer). Well, when you are about to choose what type of installation it will be (Gnome or KDE Workstation, Custom, etc.) you may choose whatever you planned before, but I would suggest to install a Workstation at first. This is good because Linux setup will find automatically the free space on the (first) hard disk, make all partitions needed for Linux, format them properly, make majority of option by default so you won't have much pain during the setup (later, if you want, you may either to add missing components or re-install Linux as Custom over the existing linux partitions). Lilo should go to the MBR.
After it looks that Linux installation is finished, you are going to re-start the computer and there there you will only see Lilo with one Linux entry to boot (or maybe more than one Linux entry, in case your hardware is multi-processor one). But, don't panic! Your Windows NT is still there where you had installed it before Linux. You should become some familiar with Linux as soon as possible, in order to be able to find and edit your new /etc/lilo.conf file. When you open this file for the first time, you'll see that there is only one (or more) Linux entry. Well, you should know the exact position (read: a partition) where Windows NT has been installed, so you could add an appropriate entry into /etc/lilo.conf file. After you do that, restart Lilo and, after the next re-boot, you will have both 'linux' and 'nt' entries under Lilo menu.
Well, you may use the same procedure as described above. I suggest you to read Linux+WindowsNT mini-HOWTO that also talks about booting Windows 2000, which is installed on the same part of disk where Windows NT was before. There you'll find many useful details regarding various Linux+WinNT/2000/98 combinations.