Wow, I think I can help on this one.
Try the link.  Its for the 82801DBM south bridge and may have what you are hunting for.
ftp://download.intel.com/design/mobile/datashts/25233701.pdf
Take a look at section 5.12.8.1.  That may be able to give you the information you are looking for.
section 9.8.3.5 has all the info about throttling but not sure if its what you are looking for.