just leave your installed lawlessppc leo 10.5.4 and put IATKOS v7 DVD into your drive and boot from dvd rom, then press F8 and boot with this cmd rd=diskXsY where X stands for the number of disk on which you installed LAWLESS distro and Y stands for the partition number of disk on which you installed LAWLESS distro. examples: in my case
disk0s2 (first disk, second partition)
then hit enter it takes 2-3 min at grey apple screen and keep your eye on HDD LED or DVD LED lights repeatedly if not try again, then your lawless ppc leo 10.5.4 distro must boot, in my case it worked, i think it load all kexts from iatkosv7 distro then boots into lawless leo 10.5.4 distro.
try this may this help