A script isn't necessary. Start with a couple of variables to store the X and Y of the center of the map. Then, start a "Loop...End Loop" segment. Inside, have your four conditionals that check for a direction pressed, but instead of moving the image when a key is pressed, change the X or Y value in the variables that represent your picture's coordinates. So, if the user presses the right arrow, subtract 1 from X (remember, you're scrolling, so you need to think in the opposite direction of what would seem normal). Then after the four conditionals, but still inside the loop, have the picture move to the X and Y variables in reference to the center point. Add a "Wait 1 Frame" statement just before the end of the loop so it doesn't hang up on you. You can also add additional waits if it scrolls too fast. Lastly, have a conditional to check for the action key ('C') being pressed, and when it is, you should delete the picture and jump to a label outside of the loop so the player isn't stuck forever.
With this method, you can also check when the variables reach certain limits (like, the edges of the screen) and either stop the player from scrolling further or have it wrap to the other side.
