I’ve added this document, which is just a listing of offsets from the Suikoden III save file. The data from the save file is (obviously) loaded into memory and luckily the offsets in the save file correspond closely to the offsets in memory. Those that are listed don't deviate at all.

I typically work with respect to where Hugo resides in memory and in the save file. If I find something promising in the save file then I calculate the difference between that location and the start of Hugo's data in the file. The difference is then used to compute the likely memory location.

You need a Xport or some other type of save game utility to pull files from your PS2 memory card. In order for the information I have provided to be useful, you also need the Save Slicer tool that can be found on the Downloads page. Once the save is on your PC, use the saveslicer to extract the "gamedata" segment from the file. It is possible to make use of the exported save file without slicing it, but the offsets will be higher and may differ between save utilities.

This is by far the easiest way to hack Suikoden III. The SLUS file lacks useful code labels and most of the promising text labels are only loaded from dead code.

It is also possible to modify the save file directly and upload it back to your memory card. The gamesave has a checksum on it that must be repaired however. I“ve never bothered with defeating it, but if you want to try, feel free. I do request that you fill me in if you are successful ;)

Additional resources:
A pre-sliced save file.
Same thing Xported to text and with a Hex Editor view applied.
If you lack a save download utility, this may be handy as just reference and you may even be able to hack codes with it. The file is from chapter 5 with Hugo as the Flame Champion.