I've got almost the same laptop. I think it's SB450 bridge. I've inject IOATAfamily.kext into DVD but now its says Still waiting for root device. I've installed it on external hdd, so whats the best way to copy it into my HDD?

Back to your problem

I've got the same. It's not exacly problem with Firewire but with graphics, just try to

boot with -s

mount -uw /

cd /system/library/extensions

and remove GeForce.kext with rm -r

rm -r GeForce.kext
rm -r Ge*
rm -r NV*

Hope it helps.