You'll need to install the Small Man newgrf from the in-game content downloader. You want your map settings to give you as flat a map as possible. 0 towns become cities, cities as small as possible, no variety distribution, very flat, no rivers, custom sea level as low as it will go, freeform edges, 1 town, industry funding only.

When you start, press 'l' then 'p', this opens the object menu. Now place the object twice, this'll net you 22 billion, open the money menu using 'f8', and repay the loan by pressing the repay button while holding 'ctrl', and then immediately split.