So how exactly does one go about doing this?

I was able to open it and edit the parts I wanted, but from then I could only save it into a text file.

I figured maybe that's what ConvertData is for, but I have no clue how to work it, and all the documentation I've found on it is really vague and doesn't help at all. I also tried the ConvertData GUI thing by Zanyth0x42, but there doesn't appear to be any instructions on how to use that either. Trying to wing it resulted in an error message stating that "ConvertData.exe is not an executable."

Help would be greatly appreciated.