I'm not sure what all information will be needed in order to help, but here's something for starters:

I'm creating a serial reaction time task, where when an asterisk appears at a certain position on the screen, the participant presses the corresponding button as quickly as they can.  The stimuli are presented on a slide, and the input comes from they keyboard (keys 1, 2, 3, 4).  If there is any other information needed in order to help, let me know and I'll do my best to provide it.

If anyone could help with the writing of a script that would do this, please let me know as soon as you can.  I'm on a bit of a deadline with this project.