In case anyone else out there is looking how to permanent change their mac address on the razr hd, I found the file responsible:
/system/etc/firmware/wlan/prima/WCNSS_qcom_wlan_nv.bin
Which is actually a symbolic link to:
/persist/WCNSS_qcom_wlan_nv.bin
You need to use a hex editor instead of a text editor to modify it. The mac address starts at the 11th byte. All I did was I used ES File Explorer to copy the file to a windows share, edited using a hex editor (XVI32), copied it back using ES File Explorer, and rebooted.
Copying and pasting to either location should work. I did the one in /system not realizing it was a symbolic link and it worked fine and ES File Explorer maintained the link. However, it probably would be better to modify the one in /persist since that is the real location.
Also in case you want to double check, the permissions on the file are 660 (-rw-rw----) and the owner:group is wifi:wifi. Copying over the top of the existing file kept these settings.
Cheers
