The two trainer hacks have a very narrow application time. Before the game starts a screen with pasteraki written on it flashes two times. The hacks need to be applied after the first flash but before the end of the second flash (there's a black screen in between). You'll need to freeze the game while applying the hacks. One makes all the prices drop so you can stockpile, you then refresh the game and apply the other one to make the prices skyrocket. It's a bit messy but that's how the game was designed 

Any update on the 4b*8+6 change?