It most certainly does have an ACPITBL module. I will attempt to decompress the bios tomorrow. BIT.exe can decompress it, but I have not yet been able with the cbrom to do this.. I will take a couple minutes this week to look further..
I modded a p4s533-mx and a p5s533-x a couple of years ago, I still have the succesful mods on my hdd. If either of these are the model i'll upload.