From: http://members.cox.net/wrt54g and http://docs.sveasoft.com

1.  Download the firmware from ftp://ftp.sveasoft.com or
    http://www.sveasoft.com/modules/phpBB2/dlman.php (Public/Stable Firmware).
    Firmware_Satori-4.0G.zip (stable, 30 Jun 2004)
    Firmware_Samadhi2_v2_2.00.8.6sv.bin.zip (obsolete, 08 Mar 2004)
2.  $ unzip Firmware_Satori-4.0G.zip
    inflating: Firmware_Satori-4_0G.bin
3.  $ cp Firmware_Satori-4_0G.bin code.bin
4.  Look up the linksys-tftp.tar.bz2 file on the internet and download it.
5.  tar xvjf linksys-tftp.tar.bz2, cd linksys-tftp; make; mv linksys-tftp ~/bin
6.  Connect the computer with Firmware to LAN utp port and give it IP
    192.168.1.1 (netmask 255.255.255.0)
7.  'Long reset', hold the reset button down for 10-15 seconds until the device
    reboots. This will reset everything to defaults. The reset button is
    located between the LAN port and the antenna.
8.  Open browser voor http://192.168.1.1
9.  Log in with the default password.
10. Look for "Factory Defaults" in the adminstration menu, select "Yes" and
    then click "Apply".
11. Go to the management menu and set boot_wait and tftpd daemon options on.
    Save settings.
12. $ linksys-tftp 192.168.1.1 # linksys default IP
13. Type on the 'linksys-tftp>' prompt 'put code.bin admin', BUT DO NOT TYPE
    <Enter>.
14. Reboot wrt54g and press <Enter> after you see the first LED light up.
15. Wait for OK from linksys-tftp program.


After Updating
1. Point your browser at the linksys IP again and log in.
2. Look for "Factory Defaults" in the adminstration menu, select "Yes" and
   then click "Apply".
3. Once the "Factory Defaults" are complete, re-apply all your settings.
4. Once all your settings are back in place, unplug the WRT54G, wait 5
   seconds, then plug it back in.