Add graphic to track 1 and nest.
Double click on this Nested Sequence: animate the graphic.
Back to main timeline. Add mask to track 2.
Add track matte effect to track 1 (Nested Sequence) and set it to track 2.
I'd probably just add the necessary Position keyframes to make the graphic 'scroll', then add the Crop effect to constrain it's visibility to the Title Safe region.