To start, which wiki page did you use? The segment under 'Example' here worked for me. This didn't do anything useful for me. I'm running this on WHR-G54S routers. DHCP is disabled on the branch end of the link, and the source end is forwarding DHCP from a separate server. Once I followed the instructions in the first link (with no security at all for initial setup) and had it working, I then stepped up to WPA/PSK (AES) and it linked up again with no problem. WPA2 gave no sign of life. I've got the two routers in boxes right now to take to another site where they'll be deployed tomorrow, but I'd be happy to check any more settings you'd like me to look at as soon as they're back on the LAN.
For what it's worth, I just verified that it works with WPA on a WAP54G running DD-WRT as well. I might be able to borrow a WRT54G and play with it, but no guarantees.