For what it's worth, I got as far as running the SL installer at some point. I could run all the utilities that come with it. I even had a network connection. However, invariably, I would get a KP after some significant disk activity on the install volume, about 1 or 2 min. into the install.
I have tried all I could think of: dsdt from my 10.5.8, graphics string from my 10.5.8 in c.a.Boot.plist, kernel flags, different combinations of kext's, EFI based, /Extra-based... you name it. No success whatsoever.
My box is as follows: GA-EP45-DS3R, f9 BIOS (10.5.x config), Intel Core 2 Quad Q6600 2.4GHz, Nvidia 9800GTX 512MB.
Any helpful hints much appreciated!!