I think another asked the same question recently but called it a graphic boot screen for lilo. See if it is what you are considering. A user posted a link to a website with some info.
BTW: I think the other distros are probably based on a boot loader called grub, at least I know SuSE is. But I see no reason why it couldn't be used with Slack. Myself, I like lilo because it so easy to configure from just a console prompt. Sometimes that may be all you have from booting a CD or floppy disk.