[FaradayCage]

Eleventy! So with an Airport Extreme 802.11n enabled, Macs on both 10.4 and 10.5, I was able to revive my WRT54G v4 with dd-wrt v24, RC7. Well, burn my motherboards... I was able to set it up and get it to work. On the Airport end, you have to use what the Airport calls WPA2 Personal security, NOT WPA/WPA2 Personal. This requires you to set the dd-wrt repeater to WPA2 Personal, with AES only as the authentication. Don't use WPA2 Personal Mixed. I left the Advanced Settings authentication to auto, not shared key. The instructions here look pretty solid:
http://www.dd-wrt.com/wiki/index.php/Repeater_Bridge
but didn't specify which security protocol to use. I was only able to get WPA2 Personal to work, which is plenty secure for most of us. Didn't try WEP, why bother? I'm not sure that it is necessary to set this up as a Client Bridge first, as the instructions say. But do remember, if you have an Airport basestation, that you will be changing the IP on your repeater from the standard 192 octet to 10.0.1.2. And from thereafter, once you have applied settings to the repeater, you will have to login at the 10 dot address, not the 192. Also, in the course of changing firmware to v24 RC7, note that you may have to login as "root" and use "admin" as password. That hung me up for some time until I saw a post that older versions of dd-wrt required "root" as username. If you leave username blank, it may not work. That almost made me quit until I saw the post.
I tested joining the network of the repeater, and it demands a password, so the security of the repeater works. Naturally joining the Airport still requires a password as well. Which reminds me, when you set up the virtual interface per the above URL, make its wireless security identical to the physical interface.
I've done all of this because my older iMac G5 get craptacular reception in my building, but now I have a hearing aid on it!
I'm posting this now, without my iMac's built-in wireless, through the repeater. Hoo!