what happens when you try to run lilo?
sysimage sound like thats the rescue cd's lilo?
to re-enable your old lilo.conf overwrite the config you are using. then just run lilo. if you can access man pages on your rescue disk run man lilo there are options to read from other lilo configs. if you dont want to for some reason overwrite it or cant. the rescue cd might be mounting your system read only