Either win this properly, the quickest being through gambling, or getting enough Ports to gain a high income.
For gambling, keep rising up the ranks until you are high enough to play against Wim Hovenkamp in Nevis. The stakes are at 100,000 Piastres per bet for the first time you bet against him, quickly bringing you to 1,000,000 Piastres easily. After winning, the max bet will be set to 10,000 Piastres.