We have to just insert a line "macaddr=XX:XX:XX:XX:XX:XX" in the nvram.txt
Here is how I did it:
1.)First pull the nvram.txt file from /etc/wl to sdcard:
in cmd(windows) goto android-sdk-windows\tools and type
2.)Copy nvram.txt from /etc/wl to sdcard
cp /etc/wl/nvram.txt /sdcard/nvram.txt
3.) Using text editor in phone add following line at the end:
macaddr=XX:XX:XX:XX:XX:XX (replace XX:XX:.... with desired mac addr.)
4.)Save file and copy it to /etc/wl from adb shell
cp /sdcard/nvram.txt /etc/wl/nvram.txt
5.)Reboot and it is done.
To restore orignal mac address just delete the macaddr line.
1.) Tested only in stock LG rome with GNM OC kernel. In other roms or kernel the location of nvram.txt may differ according to the parameter using which driver module (wireless.ko or bcm4325.ko) just find that file and use the above process. It will work.
2.) The file cannot be edited in windows as windows has different new line character than linux. It has to be edited in some linux compactible file editor like Programmers Notepad.