IIRC,
The x-arcade encoder (assuming it's the same in this revision) operates differently electronically than the ipac/keywiz... I don't remember the exact electronic reason (or have it backwards), but it's also the reason you CANNOT use the x-arcade encoder with Perfect360 sticks...
I think it's because at "rest" they are at "active high" (+5v?) where as the other encoders are at 0v low... or vice versa... i'm really fuzzy on the details... but the encoders are very different in this regard it's not just a pin incompatibility...
Now that's not to say taht some bored EE can't work an adapter to the adapter... but it's probably more trouble than it's worth, and you'be be better off hacking a playstation pad and getting the usb/xbox/etc adapters like from lik sang or what have you...
*shrug* again, don't pick me apart too badly on the exactly description, but there's something to what i'm trying to get at above...
rampy