I'm not an expert, but I think you may need to answer the question of why should the Europeans add Papaua New Guinea to their colonial empires (other than just simply for prestige) and heavily develop/exploit the area. True, there were a lot of resources to be exploited, but the Europeans (with a possible exception from the Dutch) didn't know that until very late in the colonial era, and they basically didn't do much with it.
IMO, you probably would need an earlier exploration of Papua or make it the backbone of some country's colonial empire, like how the British viewed India as their "Jewel in the Crown". Get some early adventurers to go on an expedition there and get some authors to popularise the area in the public mind.
EDIT: There was one Italian author that seemed to have a thing for the East Indies and even had a popular following: Emilio Salgari. With a few butterflies, he could popularise Papua enough so that the public (or at least some business interests) would keep an eye on it.