I've done a 10.6 install to a SATA partition from an existing 10.5.8 partition on the same disc, using a retail SL DVD and myHack installer. The install went okay I think, but I have some problems with hardware.

Using the VoodooHDA kext and some additional modifications, I now have sound (onboard Realtek ALC888). But modifying the yukon info.plist in ionetworkfamily.kext with my device info didn't help with ethernet (onboard Marvell Yukon 88EC039). Before, in Profile->Hardware->Ethernet displayed my raw hardware info, and now is says there are no PCI cards installed.

Graphics (GeForce 7600 GT 256) with an EFI string in boot.plist seem okay at first, full widescreen resolution, and the system boots super fast (about a minute to X, including mostly verbose text output, as opposed to about 6 minutes in Leopard), but for the first few minutes it displays only the mouse and a snapshot of the desktop on which you can't click anything (although the clock in the menu bar keeps moving, nothing else can be clicked). And reboot/shutdown still doesn't work, but that is the least of my concerns after everything else.

I've zipped and attached all the boot logs and info I can think of, in hopes someone has some suggestions on getting ethernet, graphics, firewire, etc., working with a kext, dsdt, or otherwise. Thanks for your help.

hmmm ... after all that, it looks like the log file attachments didn't post; please see:
deesto private pastebin - collaborative debugging tool