Linux 2.6.0
Finally got it working! Steve Kemp gave me the solution to my problem:
image=/vmlinuz
label=Linux
read-only
initrd=/initrd.img
append="root=/dev/hda2"
After putting this in Lilo, loading mousedev and psmouse modules made the /dev/psaux mouse (and the X) work:
> uname -r
2.6.0-1-686