Upgrade a Linksys WRT54G Version 5 Wireless Router Firmware
Upgrading a Linksys WRT54G v5 wireless router is a bit more complicated than most of the other Linksys WRT54G wireless routers. It is not as easy as downloading a dd-wrt .bin file and uploading it via the router administration GUI. Instead you must first install some other bin files to wipe the wireless router clean and then install the dd-wrt software.
Follow these instructions and your wireless router will be running dd-wrt software in no time.