Have you tried using System->Scroll To action and setting the scrollX (or scrollY for vertical) to how far you want to scroll each tick?
Try this:
1 - Create an every tick event
2 - Add an action to the event and select System->Scroll To X
3 - In the value field enter "scrollx + 50" without the quotes
4 - run the program and see if it gives you the result you want.
If you want to pause at each scene, just add a boolean condition called scrolling to the event and set it to true only when you want the scroll to happen.
[Edit] Just wanted to mention you can change the speed of the scroll by changing the amount you add to scrollx