Well, I could write a guide, but not now: once I get back from vacation, I start school. I have about a week of class, and then a other one off, so expect it around that time.
Since I don't have the comp in front of me now, I can't even try stuff.
But from what I remember, the edits I did are the following:

• Renamed devices (LPCB, MATH, etc)
• Added speedstep info in the procesor section (for i7 920)
• Added Device (SBUS)
• Added the HDEF call and device HDEF

I have done other minor fixes, that I really don't remember and probably never will be able to differ from the DSDT. I guess I could just "look for changes" or something, but that would probably take days... I just might do it, I'll see.
To add HDEF to your DSDT, just search for the line on top of "Device (HDEF)" in your DSDT and then copy the code I posted under it. Remember to leave a line in between. Then do the same for that other line, it should work. I doubt that it needs any other edits for it, maybe Device (SBUS)...