From the amount of posts requesting help on this technique it should be a high priority for any developer of plug-ins or even Madison itself. But it looks complicated, even for a non-programmer. And once they create a solution, someone will want it for another font, with international characters, and right to left.
If you create a veg for each character and use various techniques to progress the writing lines you could line the vegs up after one another - copy and repeat when neccessary - and thus create the image of words being written. It is a lot of work but this effect is wasted if you use it too much. And at least that way you do not start from scatch each time.
Tor
Try using one of the screen capture programs to capture video of handwriting, save the video to given format(usually .avi). Import into Vegas. It's crude, but with a little work I believe you can make something of it. I've had some luck with it...just an experiment now as my Wacom tablet is only a couple of weeks old.
Funny this should have come up. I just watched some show (sorry don't remember the name) and they'd done it real simple. Camera on a stand, pad and pencil. Just finding someone who can write neatly might be the hardest part.
Another old school way of doing this from memory, is to write on glass and shoot through the glass then key the text, you need to mirror the image but that's simple with Vegas.
There is a freebie .veg file at VASST -- BUT it's totally useless for the needed media file is missing. But the demo clip works so you can at least get a sense of it. As remarked by the last visitor there, one can use some SpiceMaster tutorial. Maybe.
A few months ago, I tried to contact the author of this freebie about the no-file thing, but got an invalid email. So I just sent VASST an email about it, but they won't be back til January 3.
Maybe eventually, this will get fixed -- and it will finally feed us hungry editors our gotta-get-one goodie :)