Alright, ran into a problem. Got 10.6.8 working just fine - QE/CI works, pretty much everything else I can think of is working fine. Except for my keyboard. I've tried both USB and PS/2 keyboards, and neither will work. I'll get to the login screen and be unable to type my password, but can move the mouse. I've tried turning USB Legacy on/off in my BIOS, and have tried both USB 1.0 and USB 2.0 in my bios - none of these allow my keyboard to work. One boot it did work, almost randomly, but I haven't been able to get it to work since.

I've tried replacing AppleHIDKeyboard and IOUSBFamily with the versions from 10.6 with no luck. Is this a DSDT problem? If so, I really don't know much about DSDT editing, but I'll learn if I must.

By the way, I have two SL installs on the same hard drive: one partition is 10.6 and the other is the one I'm trying to get completely working with 10.6.8. I did this so that if I run into problems on the 10.6.8 partition (which I am), I can boot to the 10.6 one and try to fix it.

Thanks again for your help!

Edit:

It seems I just had to wait a minute. The keyboard worked after that. Very strange!