You have to inform QA about this, because there cannot be more than one pet on the board and it has to be pre booked-they can still refuse you just like that.
Your cat should have a special passport-call your vet to ask about this.
Moreover, you should have a special cage for your pet- when you will call QA they should help you out.
Also check with your embassy, as JoeKanuck said, if they have any specific regulations in your country concerning this matter.

Good luck!