From DD-WRT Wiki
Thanks to Eko
As there were always the same questions, I decided to start a page which tells in general how you can get your Broadcom-based device running DD-WRT.
 About this guide
This guide is for Broadcom devices BUT "How to start" & "Compatibility" work for every device/hardware, except the cfe and nvram grabbing stuff. This is the updated instruction http://www.dd-wrt.com/site/support/router-detection
There are a few things to be figured out before we start. We/you need to know if its possible to run DD-WRT on it!
- check the Supported Devices page if your device isn't supported already!
Please do the following check list and if one point fails your device will be not able to run DD-WRT!
- check the Known incompatible devices page and read it carefully. if your device is listed or fits into the incompatibility information...you're out of here
- open the device and check if it's Broadcom based (cpu) or is there the FCC-ID printed on a label? check on FCC.gov with the FCC-ID if your device is Broadcom based (internal pics)
- open the device find the flash chip. check out the chip @ Datasheet Catalog and if it's <2MB, you're out.
 How to start?
Now that we know that the device is able to run DD-WRT you should do this:
check with a forum search if the device isnt already requested!
if not, start a new topic @ the forum with the subject: "your device with revision" give us all info we need for starting
- internal high res pics of CPU, RAM, FLASH, PCB
- maybe RAM/FLASH size and type and CPU type if already known
and if possible
 3rd party firmware already installed
if you have already running a 3rd party firmware (dd-wrt, svesoft, openwrt,...) you can try this to get the cfe: CFE backup by telnet/SSH
only if you are instructed to flash a special dd-wrt version for initial flash and it will not brick your router please give us cfe which is quite easy as you see here: CFE backup
In both cases from above you can get a copy of the nvram if you do a "save settings" and name it nvram.bin
Also don't forget to get a nvrambak.bin for us.
 We finally installed DD-WRT but no button/led working
This page describes how to detect the correct GPIO's for LED and reset button when you have a device which is WIP for running DD-WRT.
 Detecting Reset/WPS/AOSS/etc Button
1. telnet in and then...
try to find gpio for the reset button.
gpio poll number from 0 to 8. e.g. Code:
gpio poll 4
Then press the reset button in and out and look for changing numbers and report us like this.
gpio 4: pressed = 00 unpressed = 01
Plz only report the gpio that changes. :-)
 Detecting LED´s (and their colors)
1. telnet in and then...
try to find for the LED's
gpio enable number , gpio disable number
gpio enable 1
gpio disable 1
go from 0 to 8
If the router stops responding, just power cycle it.
List your findings at the post/to the person who asked for it!