Im Datenblatt habe ich folgende Passage gefunden:

Interrupts
The External Interrupts are triggered by the INT0, INT1, and INT2 pins. Observe that, if enabled, the interrupts will trigger even if the INT0..2 pins are configured as outputs. This feature provides a way of generating a software interrupt. The external interrupts can be triggered by a falling or
rising edge or a low level (INT2 is only an edge triggered interrupt).

INT2 kann und muss man daher nicht konfigurieren. Mit den Zeilen

On Int2 XXX
Enable INT2
Enable Interrupts

müsste es gehen.