• AtherosROMKit This is an Atheros ROM modding and recovery kit.

It has the following projects:

• Atheros EEPROM Tool RW512 (AnV)
• Atheros EEPROM Tool RW512 Windows 8.1 (AnV)
• dumpathrom (AnV)
• iwleeprom (AnV)
• AR9285_Optimized_ROM (AnV)
• iwleeprom (MacNB)

UPDATE: Here is overriderom.patch , which allows you to override rom of ath9k-driven card for testing, recovery, etc
It is writen for 4.4.16 lts version, but most likely it is usable for other versions due to ath9k source code is not being changed often.
Refer to http://www.insanelymac.com/forum/topic/299732-atheros-9k-series-rom-modding-tools-and-recovery-kit/ for some additional info.
Usage :

mv overriderom.patch ${kernel-source-root}/drivers/net/wireless/ath
cd ${kernel-source-root}/drivers/net/wireless/ath
patch -s -p0 < overriderom.patch

ISSUE
Overriding ROM is not configurable and enabled by default (using #defines directly in source code). Fixing of that is welcome