I made a failed attempt to replace DD-WRT with OpenWRT, but unfortunately the wireless NIC’s are not supported. When I returned to DD-WRT I decided to update to the latest recommended 24 preSP2 Build 14896 (04/23/10), and add support for multiple wireless LAN’s. One LAN is dedicated to the devices I do not control or trust (TiVo, Wii, etc.), and the other is dedicated to my machines.
I followed the instructions on the DD-WRT wiki, and it worked great! Per the instructions I used the Command Method to configure dnsmasq.