Well that didn't work so well, after mucking about all morning I'm back to square 2 again.
So replaced my original Ati kexts, restarted and went to ioreg | grep ATY in the terminal.
And got:
| | | | +-o ATY,Vervet@0 <class IOFBStub, id 0x10000034e, registered, $
| | | | | +-o...