I’m still working to perfect the text crawl, because there is NO tutorial yet that can replicate the original effect. What you usually get is a poor approximation, in my opinion. Thus far, Sony Vegas seems to be the WORST application for this particular effect, because it does not properly support elements that are larger than the frame (there is no true panning geometry).
I’ve tried both a text box and an image of the text. In both approaches, Vegas insists on either resizing, re-scaling or clipping the crawl text *as if* it were being viewed entirely in a 720×480 window.
The bottom line is that its not possible to maintain clear typography AND correct perspective within the same event. Pay close attention to all these SW crawl tutorials and you will see a “slit” effect.