[coreboot] Externally flashing Coreboot using microSD as external programmer

[HD Scania]

As my title suggests, what to be prepared for _‘‘externally’’_ flashing Coreboot on a microSD?
If external flash is done, *what* to be prepared to port Coreboot for my Sony VPCCB17FG laptop, with known supported Intel *HM65* chipsets, but even the vendor, Sony, is *unknown* to be supported or not?
Are there any up-to-date wikies or docs on committing like this?
> (Reference: https://mail.coreboot.org/hyperkitty/list/[e-mail]/thread/62E6I...)