I just threw a slack 10.2 install on a old PIII Dell Optiplex. I chose the default install options for lilo (I think it is 1024x768). When I boot up, after I choose Linux from the Lilo menu, the monitor goes blank and tells me "Cannot Display this Video Mode". Slack 10.2 defaults to run level 3 so I know its not X causing trouble, its got to be that stupid penguin picture and the 1024x768 resolution that LILO has when booting my system.

Is there any options I can pass at the lilo menu that will allow me to boot? What else can I do? I don't have a boot disk, although I have another PC running slack 10.2 nearby.

Don't remember a thing about LILO, but:
Try another monitor,
Log in via ssh and fix it,
Install GAG boot loader over LILO,
Study the manual how to boot manually with LILO...