I tried to flash the 8 MB Chip on my X230, but it didn't worked out.

Me: what do I need to do to flash the 2nd (8MB) chip.
If the 1st chip contains the last 4MB of the file, I assume the correct command could be:
dd of=chip8mb.rom bs=1M if=build/coreboot.rom count=8

Is this correct? If this is right I'll add this to the wiki as soon as I have write permissions.

I've dd'ed the first 8MB of the coreboot.rom file with the above command and flashed it on the 8MB chip, but when booting my machine only illuminated the on-off-button for a second before it dies.

When reflashing the 8MB chip with the stock image which I grabbed before will bring my laptop back to life. As such it seems that there must be another was two flash both chips and to strip the coreboot.rom image.

Any ideas what went wrong?
As all howto's I've found so far, which cover the flashing of only the upper 4 MB Chip, the question is also, if someone has already flashed both chips and what (s)he did to make it work.