Upgrading from a 2.2 version kernel to a 2.4 version kernel is straightforward. If using lilo5.4 you will be required to add the following line to /etc/lilo.conf:
initrd=/initrd.img
You are reminded of this on each upgrade. This message can be turned off by adding the following line to /etc/kernel-img.conf:
do_initrd=Yes
If using grub none of this is required--the kernel update is automatically added to grub's menu.