With the chatpad things are more tricky as you have to manually init the thing and then do something to keep it talking. At the moment it just stops after the first keypress and it also stops every now and then when one is sending other commands to it. And at that point I am stuck, as I have not much clue about USB or driver programming in general, its mostly trial&error.
Most of my findings are documented in (not very well organized):
And some of the other files in the xboxdrv git repository.
PS: I don't think your irq message ever reached me, I just stumbled across your post here.