From DD-WRT Wiki
Linksys WRT54G-TM and WRT54G-RG are identical in terms of hardware, but not firmware. You MUST USE THE CORRECT firmware files. The WRT54G-TM was a t-mobile router put out by Linksys, and the WRT54G-RG was a Rogers router put out by rogers in Canada.
- Download the CFE_Updater-WRT54G-RG.bin from here: ftp://dd-wrt.com/others/tornado/CFE_Updater/
- For the RG Router double check that you got the file with RG in the filename!
- Download the TFTP.exe file from here: ftp://dd-wrt.com/others/tornado/Windows-TFTP
- Download the svn 12548 NEWD_Mini.bin (NOT NEWD2!) file from here: ftp://dd-wrt.com/others/eko/V24_TNG/svn12548/
- Read the peacock announcement here: http://www.dd-wrt.com/phpBB2/viewtopic.php?t=51486
- Do a proper hard reset on your router, according to the instructions at note 1 of the peacock announcement. Because you do not have dd-wrt firmware on the router at this point, you will not be prompted for a password.
- Connect your computer to your router with a lan cable, connecting to a LAN port on the router.
- Set your computer to a static IP address of 192.168.0.17 and a 255.255.255.0 subnet mask.
- Open your browser window to 192.168.0.1. You should see the linksys webgui. If you don't power cycle your router.
- Go to administration, firmware upgrade
- Select the file CFE_Updater-WRT54G-RG.bin (the one you downloaded in the first step) and click upgrade.
- GO FOR A WALK for at least 5 minutes. IF YOU TOUCH YOUR ROUTER YOU WILL LIKELY BRICK IT!
- Change your computer to a static IP of 192.168.1.17. THIS IS VERY IMPORTANT!
- Open a command window and try to ping 192.168.1.1. with the "ping 192.168.1.1. -t" command. You should get some timeouts. When you get a ttl=100, wait two more minutes. Keep this window open.
- Open up tftp.exe
- Select the address of 192.168.1.1. Leave the password blank. Set it to 99 retries and pick the file dd-wrt.v24-12548_NEWD_mini.bin that you previously downloaded.
- Hit upgrade.
- GO FOR ANOTHER WALK. WAIT AT LEAST 5 MINUTES. Watch the ping window. You should see ttl=64. When you do, wait two more minutes.
- Set your web browser to 192.168.1.1. You should see the dd-wrt password page.
- Power cycle your router.
- Try to open the webgui again a 192.168.1.1. When you can, change your password and user name to anything.
- Do ANOTHER Hard reset on the router. Again try to open 192.168.1.1. When you can, you should see the password page again. Now finally set your password and configure your router.
- Set your computer back to auto IP and auto DNS.
If you wish to use another build rather than the mini build, you can upgrade with the webgui, following the instructions at note 1 of the peacock thread. This router will take any generic build.
Please note that there is no way to go back to Rogers firmware on this router without a jtag cable and a stock rogers wholeflash.