While I was searching for a more permanent way to change my wifi mac address, I discovered there is a util for Texas Instrument wifi chips. It is called "calibrator". The wifi mac address can set in the nvs file. Here is what I did.
root@android:/system/etc/firmware/ti-connectivity # calibrator set nvs_mac wl1271-nvs.bin xx:xx:xx:xx:xx:xx
more info: https://github.com/gxk/ti-utils
I have the HTC Amaze and rooted. You might also need to mount /system with RW. I can't speak for broadcom chips however.
