You can make a sort of copy of your firmware using "sudo flashrom -r backup.rom" in ChromeOS. You'll then need to download and compile a program called "Flashmap" to get at the ROM's layout. Then you'll need to extract the RW_LEGACY slot CBFS (if there is one). Or, I can do it for you with a shell-ball ROM instead. The more models supported the merrier! And, maybe it's just a case of generating/regenerating an appropriate CBFS with a new version of SeaBIOS in and flashing that (as Matt alluded to). The latter wouldn't even require you to disable write-protect.
sebastian grigo
18.08.2014