I have a keyboard that always comes up at unrecognized. Can I disable osx from telling me?
The solution should be a proper kernel extension provided by the vendor or someone else. 

I can tell you what can't help: ControllerMate, KeyRemap4MacBook, Secrets or some other utility for hidden settings, nor USB Overdrive last time I checked. 

You could try to ask around those devs if anyone wants to get famous a little.

My present incarnation of that issue: some Logitech and MS mouses(!) manage to trigger that dialog! Logitech even admits it, saying 'just dismiss it'. The drivers they provide are not totally satisfying yet, to quote Colonel Panic's words.