I upgraded to 10.6.5 by downloading the combo upgrade file and installing it. Once you install 10.6.5 upgrade combo and before rebooting replace the the IOUSBFamily.kext and the IOUSBMassStorage.kext from S/L/E with the corresponding kexts from 10.6.4 or you will loose the USB functions (copy them to where you can access them, the desktop is fine, before you upgrade, then use the kext utility to install them). Also remove the AppleHDA file installed by the upgrade. You should already have the kernel renamed, so will be using the previous kernel. With the latest VoodooHDA just about all functions of sound work.
Everything works on my machine. This are the kexts I have on /Extra/Extensions/: AppleIntelPIIXATA2.kext, Disabler.kext, EvOreboot.kext, fakesmc.kext, SleepEnabler.kext. I have VoodooHDA.kext in S/L/E/.
Interesting - I followed the method from teatime's video to upgrade from 10.6.3 to 10.6.5. The 3 kexts that were preserved in the video did not include the USB kexts you mentioned - but I am using my USB keyboard/mouse/flash drive without any problems following the upgrade. I wonder if the difference is bios settings? Are you using the DSDT.aml from the first post?
I will try Disabler & SleepEnabler in /E/E again. The SleepEnabler.kext I found is supposedly for 10.6.5; I wonder if that is the problem. Where did you get your SleepEnabler?