Forget using Pan/Crop in this case and use keyframes instead.
Open up a text event.
Change the text event size from 720 x 480 to something like 720 x 1,000.
You can adjust the 1,000 value lower or higher later if necessary.
Change the event length to 30 sec.
Enter all your text.
Go to the beginning of the event on the timeline in the text window.
Change the Y value in the Placement tab so that the text is in the proper starting position (around 4.0).
Create a key frame here.
Go to the end of the event on the timeline in the text window and adjust the Y value so that the text is in the proper ending position (around -4.0).
Create another keyframe.
That should do it.
Play it and see if this is what you want.