Short answer, read README.mb
It comes with the package. I can't remember exactly where it puts it, so you might have to go looking... try "man README.mb" or as a last resort "find / -name README.mb".
Long answer (WARNING: CAN BE DANGEROUS IF YOU MAKE A MISTAKE):
nvram-wakeup comes with a program that can detect all the time locations in the BIOS. Watch for *any* warnings when running it. I went through it and failed to notice a warning/error about the checksum location. Surprise, surprise, when I ran it, I got a "BIOS checksum error". I almost had a heart attach. Luckily, the BIOS was able to load the defaults.
What I ended up doing was going into the definitions of motherboards in the nvram-wakeup source. I noticed that my MB was supported with various versions of the BIOS, but not the one I was running. In this case, you can just up/down grade the BIOS to a supported version. This isn't exactly what I did, but I'm not going to recommend what I did here
Let's just say I got lucky...
Allen
