I just tried compiling and installing the 2.6.5 kernel as per a guide I found on here. Can't find the post now, it was something like "Newbie Guide to Installing Kernels"
Anyhow, towards the end of the instructions, it says to run "sbin/mkinitrd" but this was not found on my system. I found a command called something like lvm_createinitrd. I tried this and it appeared to work. I then edited and saved lilo.conf to the new kernel, but then when I tried to run "sbin/lilo" it said that it wasn't found either. I rebooted anyway and found that I had an unbootable system.
Any help or suggestions?

Do you have a boot disk?

If not, reinstall the slack 9.1.

lvm_mkinitrd isn't the same than mkinitrd. Other creates a ramdisk to boot to a logical volume and the other loads modules to a ram disk.

I have not heard of eather commands, I use the builtin kernel compiler stuff and manually copy the produced file. if the instructions were any good they would have told you to backup your old kernel so you could boot back in, if not you may need to re-install, it depends on your distro/knowledge.

yeah, I'm gonna have to re-install... not to worried about that, because I hadn't really done anything with Slackware yet. Just installed it and then tried to upgrade the kernel so it would support my nForce2 chipset.

Any good guides that you guys recommend for installing a new kernel in Slackware?

FYI, Slackware current has the newer 2.4.25 in it's .tgz format. It's really very easy to use them for upgrading.