Hex Codes:
This is a fairly advanced cheat. If you don't understand hexing then don't try it.

65535 Gold

Go to hex offset 0000 0040, change the current value (ex: 0C23) to FFFF

65535 Special coins

Go to hex offset 0000 0044, change the current value (ex: 0C23) to FFFF

65535 Magic coins

Go to hex offset 0000 0048, change the current value (ex: 0C23) to FFFF