for that option, you should edit /etc/lilo.conf, you'll have something like this
Code:
# VESA framebuffer console @ 1024x768x64k
vga = 791
# Normal VGA console
# vga = normal
# VESA framebuffer console @ 1024x768x64k
# vga=791
# VESA framebuffer console @ 1024x768x32k
# vga=790
... I've cut out some parts, but you can look and choose what you think is proper, save the file, maybe even run 'lilo' again, reboot and see if it works.