I have no idea how many goals we would have to score to get through in that scenario. Don't count on it, though. Ireland will give us a fit to try and save face this Euro and also want to stick it to us for Trapattoni. We will need everything to go right on that final day.
You could score a bazillion, still wouldn't help.
Rules in case of even number of points:
1/ Most points in games between involved teams. If Croatia and Spain draw, and Italy wins against Ireland, all three teams will have a draw against the other two teams (3 each), so on to next tiebreaker.
2/ Best goal-difference between involved teams. Three-way tie, with ties in all three games? On to next tie-breaker.
3/ Most scored goals in games between involved teams. If Croatia and Spain tie with 2+ goals each, those two teams win this tiebreaker against Italy.
Only after that will the tiebreaker involve best goal difference in all three games of the group stage.