I'm having similar issues. Although I think a minor degree of operator error may be involved. I labeled my UserDSDT UDSDT.ami when I mounted it to the desktop. As I understand it, I should have labeled it simply DSDT.ami.
I also understand based on some reading that I need to make sure that I have the correct DSDT.ami for the bios my motherboard is running. There are three different DSDT's listed for that motherboard. I need to examine the bios more carefully to make sure I'm loading the correct one as a .ami.
I've been able to install from iBoot, go through the process of loading once from a 10.6.3 retail install that was successfully loaded onto the hard drive, then use the iBoot CD to load from that HD install. I have gone through Multi-Beast and installed DSDT, but there may be a hiccup due to my wrong labeling, I'm not sure there. I've also gone through and used the updatehelper because the system I'm running is Sandy Bridge.
I've had the boot loader from the hard drive load, and when I click on my newly installed, and multi-beast/updatehelper improved system try to reboot, the Apple Boot Screen comes up, runs for less than 30 seconds, then there is a crash.
I'm hoping it is just operator error on my part in terms of the multi-beast portion, although I'm intrigued about the 10.6.6 update prior to the 10.6.8 update issue people are addressing.
I only wish I could get to the point where I need to update to 10.6.8. I can't get passed the reboot stage following the initial multi-beast/updatehelper stage of the Sandy Bridge install paradigm.
So is my mislabeling the CULPRIT?
I am going to give the install process another try after work tonight.