on the cs5530 southbridge, 

setpci -s 0:12.0 52.b=ee
setpci -x 0:12.0 5b.b= 0x20 (| with whatever is there)

I am making this a general-purpose userland flash burner -- RGM

Earlier notes from Ollie:

Here is some utilities for using/programming flash ROM on SiS 630/950 M/Bs

	1. flash_on, turnning on the flash writer enable for 630/950 M/Bs,
 	   you have to run this before load DoC drivers.

	2. flash_rom, use your 630/950 M/Bs as a flash programmer for some
	   flash parts. This utility is made as modular as possible. If
	   you find your flash part is not supported, you can add a driver
	   your own. Or sending me the data sheet.

Ollie