I have done a transparent scrolling credit roll at the end of the wedding films I have done. There is not much to it. The trickiest bit I found was determining its scrolling speed which is set by the length of the credit roll 'generated media' down the time line.
Unfortunately, text manipulation is something Vegas has been pretty week on from my point of view. Every time I try to hit up the new Titler in v8 I have stability problems and it is slow, so I just skip it.
If you want to take a look at two samples of ending credits I created using lots of key frames with the normal "text generator" then check out the following links:
This is a video using a LOT of tracks and layers of tracks in order
to get media files played at a slight tilt away from the screen to them do a "scroll into the background" All the text & media files are individual tracks under a parent track that actually contains the motion.
The first video on this page contains lots of motion. All these text elements were layered and keyframed using Vegas 6. Contrary motion was the theme I used for that ending credits. It may look a little busy though.
The second video on this page contains less motion. but has text chopped up into sections allowing lots of creative placement of video / graphical elements.
I have also used a few of Vegas's canned "credit scrolls" but you are limited in style and font variety, etc so I usually do credit fades instead of scrolls.