WRT54G as Repeater

1. Configure the 2nd WRT54G as an access point. Details and instructions on request or just search this group. Run an ethernet cable between the two WRT54G boxes between LAN ports. The WAN port on the 2nd WRT54G goes nowhere. You can mix and match SSID and channel assignments, but if you wanna try seamless roaming, they should both have the same SSID and be on the same channel.

2. Use WDS (wireless distribution service). This works the same way as the wired solution previous described, but without the ethernet cable. However, there is 50% reduction in maximum thruput going through the 2nd router via wireless. This should not be a problem if
your backhaul (Cable or DSL) is much slower than your wireless connection. For WDS, both boxes will use the same SSID and channel.

link : DD-wrt firware