Start a new game and build plenty of industries. Keep building to intentionally get into debt. Once you are $32 million in debt, the game will roll over the value and you will have $32 million in available funds.
When a CPU player starts the game, quickly look for that player's starting location on the map. CPU players always begin by placing a single railroad station near their company's headquarters. Buy the land on both sides of the station as soon as possible by placing a railroad track on both sides of the station, so that the CPU cannot connect tracks from it. If this is done before the CPU begins placing its own tracks from its first station, it will do nothing and will eventually go bankrupt. If the CPU has already started placing tracks from its first station, you can force it to resell the already placed track by interrupting the CPU's placement with your own railroad tracks. The computer may try to build over your tracks with ramps or bridges (at the cost of more money). You must interrupt it as much as needed. The CPU will eventually resell its tracks all the way back to its station, at which point you can block the railroad station. Doing this will give you more time overall to establish a monopoly over your current map. The cost of railroad tracks that you used to block your opponents with is insignificant to the potential amount of money you can make without competition.