I think I found how to enable BIOS chip programming. I make dump PCI config space registers device: 00:07.0 Intel Corporation 82371AB/EB/MB PIIX4 ISA [8086:7110]
while vendor BIOS and while coreboot bios and compare them. I tried to change the DWORD at offset b0 and flashrom no longer displays an error GPO26 :-)

This is log after boot debian on coreboot:
========================================================================================
root@debian:~# flashrom -p internal
flashrom v0.9.7-r1763 on Linux 2.6.32-5-486 (i686)
flashrom is free software, get the source code at
http://www.flashrom.org
 
Calibrating delay loop... OK.
coreboot table found at 0x9fe1c00.
Found chipset "Intel PIIX4/4E/4M". Enabling flash write... OK.
Enabling full flash access for board "abit BF6"...
ERROR: PIIX4 GPO26 not programmed for output.
FAILED!
Aborting to be safe.
Error: Programmer initialization failed.
========================================================================================
No try set PCI register at offset b0:
 
setpci -s 00:07.0 b0.l=e0000105
 
and now flashrom working :-):
========================================================================================
root@debian:~# flashrom -p internal
flashrom v0.9.7-r1763 on Linux 2.6.32-5-486 (i686)
flashrom is free software, get the source code at
http://www.flashrom.org
 
Calibrating delay loop... OK.
coreboot table found at 0x9fe1c00.
Found chipset "Intel PIIX4/4E/4M". Enabling flash write... OK.
Enabling full flash access for board "abit BF6"... OK.
Found Winbond flash chip "W49F002U/N" (256 kB, Parallel) at physical address 0xfffc0000.
No operations were specified.