Is there any way to get the 770 to recognize a 64 Digit WPA Key?

I've got a WDS Wireless system setup in my house ('Repeats' the wireless signal so I have full coverage in my house at the cost of bandwidth). I've got a Linksys WRT54G running dd-wrt, and I have an Apple Airport Extreme running as the WDS Node.
I used to only use MAC filtering until I saw someone spoofing an address and using my internet. I've setup WPA instead of WPA2 to support my 770, but I've run into an additional problem. The 770 won't accept a 64 Digit WPA key, but my Airport Extreme won't accept anything but a 64 Digit WPA key. I'm left with three choices, unless I can get a full length key working on the 770: Buy another WRT54G with DD-WRT, have full wireless coverage in my house, or finally don't have my 770 connect to the network. All of these options suck, frankly. WEP is not an option, the fact that someone took the time to spoof a device ID is proof enough that the same person will invest the 30 seconds required to crack WEP.