Load Death Track, type your name, choose your car, adjust your laps,
difficulty etc, start a season or whatever it is called, then bail out 
to dos.

Use a hex editor such as Norton diskedit, and edit the RCT file you 
just saved. Goto Offset 18 Hex 12, and type FF FF FF.

This will give you an ungodly sum of money.

You can, if you so desire, append one or two more FF's, for an even 
more ungodly sum of money, but this can also make the game a bit 
buggy. Besides, it's not as if you need THAT much cash.