Take the Y button for example.
Start a macro. Draw a line for Y. Be sure the line starts at zero, and goes all the way to the very end of your macro (Y should be the last thing 'still pressing' when you've finished your macro).
Now assign this macro specifically to the Y button (so essentially wen you tap Y, it'll start pressing itself). Since it's pressing itself constantly, it never has a chance to see if you are pressing it again asking the macro to play again, so it'll just keep playing itself over and over and over again.
If you need other keystrokes just insert them after 0.0 but before the last keypress which should be the Y still pressing itself.
Einar