kernel panic means that slack can't find your kernel. try booting into the system using a boot disc, then verifying that your /etc/lilo.conf file is pointing to: 1) the right partition (your /boot parition or / partition if no /boot is defined). and 2) the image is pointing to the correct version of vmlinuz (usually image=/vmlinuz). if /vmlinuz doesn't exist, you might wanna check your /usr/src/linux directory for a valid vmlinuz.
hope this helps. :-)