Reading forum

Before playing with this read this forum thread.

Creating MN-700 Bootloader Image

You have to use x86 linux box to do this. Grab reference image and config template and look for the nvserial program on the internet.

Once you've grabbed them edit mn700.txt and replace two @@MAC@@ occurences with your device MAC address (printed on the board sticker, should start with 000D3A). The MAC string entered to the mn700.txt should be as following: 00:0D:3A:xx:xx:xx

Once done run nvserial like this to produce your image:

nvserial -i mn700.bin -o cfe.bin cfe.txt

The resultant cfe.bin file is the thing you are looking for. :-) Use JTAG to flash it to the device. When flashed correctly, the Power LED should start blinking on power on, indicating recovery mode. If it does not blink - try reflashing image and clear nvram.

Once done use ASUS Firmware Restoration Tool for the WL-500g router to flash custom firmware.