To me, it seems like the best way to get to the point you want would be if the Porfiriato can be prolonged as long as possible. As many problems as the era had, it was a sustained period of peace, (relative) prosperity, economic growth, and political stability. The longer that continues the better Mexico's economic situation will be, which will lay the foundations for a developed prosperous state. Of course, the biggest issue here is that the Porfiriato was a time of tremendous inequality and the Mexican elite prospered off of exploiting the peasantry. That and Mexico's underlying Liberal-Conservative divide that had caused previous conflicts created some very significant tensions which blew up into OTL's civil war. So maybe if you can have Diaz pick a successor who takes up the reigns of power and keeps a lid on the brewing conflict, Mexico could continue to prosper. So, a bit like what Taiwan and south Korea did during their periods of authoritarian government and economic development.