flashrom can write to a growing number of BIOSes, did you try it already? It's in portage so you can just emerge it. Look at the use flag list, since you might need to enable support for something in there so it can see your chip(s).
The exe file might be usable directly with it, or you might have some luck trying to uncompress it with 7z or xz. -- Jesús Guerrero Botella
