Occasionally you may want to pass an option to the kernel at boot time. Some of the more common options are root= to specify an alternative root filesystem, init= to specify an alternative init program (such as init=/bin/sh to rescue a misconfigured system), and mem= to specify the amount of memory in the system (for example mem=512M in the case that Linux only autodetects 128M). You could pass these to the kernel at the LILO boot prompt:

LILO boot: linux root=/dev/hdb2 init=/bin/sh mem=512M

If you need to regularly specify command-line options, you might consider adding them to /etc/lilo.conf. The format of that file is described in the lilo.conf(5) man page.