I'm trying the steps gatorparrot has provided -- I just don't seem to have the timing right with my WZR-600DHP. I've tried both with the dummy MAC (02-aa-bb-cc-dd-20) as well as the device's actual MAC.
From power-on of the router, all the LEDs flash at about 6 seconds in; then it's another 20 seconds or so before the wireless connection LEDs turn on. The instructions state the connection LEDS should start at about 10seconds. I've tried starting TFTP at 6 seconds, at 10 seconds, at 25 seconds, etc. In each case the transmission over TFTP doesn't work (it times out).
Also have tried Pumpkin TFTP, the linksys TFTP.exe and TFTP2.exe programs, all without success.
Just as background for what I'm trying to do: I have Buffalo latest r30355 installed, which doesn't seem to offer a repeater bridge mode (it does not appear in the wireless mode drop-down). I'm trying to switch to community DD-WRT so I can use this router as a wireless bridge...
I've been at this several hours and can't seem to hit it right. Any other ideas out there?