You may be confusing GRUB with LILO. As far as I am aware LILO doesn't have a boot time command line.
After you have compiled the new kernel copy <kernel-root>/arch/i?86/boot/bzImage to your /boot directory [assuming you are using bzImage's] Copy the System.map file as well.
Open /etc/lilo.conf [as root] in your favourite editor [eg: [in an xterm] vi /etc/lilo.conf]
Add a new section:
Save the file then run '/sbin/lilo' to make lilo read the new configuration, and change the boot sector accordingly.
I haven't used LILO for a while, so there may be something glaringly obvious I have forgotten!