Hi,
as the subject suggests I have run flashrom on a DEC Alpha Digital Personal Workstation [1], model 433au. flashrom itself segfaults but superiotool finds a SuperIO at least.
Most DEC Alpha workstations are flashed using a proprietary flash utility which is run from the the SRM console [2]. There are several manuals on the net from DEC and Compaq which describe how to update the firmware using the original utilities, for example [3].
I have no idea so far how to enable/disable writing to the flash rom chips but I think it should not require any more magic than on x86 systems ;). Especially, because many of the Alpha systems are actually using Intel chipsets. Usually those Alpha machines have a jumper onboard which enables/disables flash write so there probably isn't the need for a specific board enable at all. Probably it's just a matter of finding the proper location of the address space of the flash chip in memory.
I'm attaching the debug logs for superiotool -dV, lspci -nnvvvxxx and flashrom -V.
Adrian
[1] http://en.wikipedia.org/wiki/Digital_Personal_Workstation [2] http://www.compaq.com/alphaserver/download/srm_reference.pdf [3] ftp://15.200.2.21/ftp1/pub/alphaserver/firmware/retired_platforms/workstations/ASTN600/alpha500_600_V72_fw_relnote.pdf