That might work. Either that, or give another confederation a quarter slot, and the rest of it go to a 3rd confederation the way they did in '94 (OFC got 0.25, CONCACAF got 0.25, and CONMEBOL got 0.5).
Here's how New Zealand got to South Africa.
Automatic bye to final round of 4
Beat Fiji 2-0
Beat Vanuatu 2-1
Beat Vanuatu 4-1
Beat New Caledonia 3-1
Beat New Caledonia 3-0
Lost to Fiji 2-0 (meaningless game, they'd already clinched the OFC-AFC playoff by then, they played scrubs)
Tied Bahrain 0-0
Beat Bahrain 1-0
8 games against 4 tiny countries. Bahrain was the toughest team they played at 61st in the world according to the FIFA World Rankings. They're 83rd. The others are 108th, 141st, and 159th right now.
EDIT: Let's frame this a different way. NONE of the final round teams from CONCACAF are ranked below New Zealand. Not even T&T or El Salvador.