anyone know where i can get a script like the one on this website or what i could search for?
http://vinylcraftlettering.com/cdc/index.php

Are you using Linux? Install MING. Then you can write a flash script which can load up any fonts you want, which you can upload onto the server. The rest is blatantly just simple javascript along with the use of png's for each font in its own name. But to make it turn the input into the writing in the font, the method of using MING and thus generating it in swf form is probably the most cross-platform friendly way. If you install gd.pm (I think it's called) you could potentially produce it, somehow, as a gif, but it'd be pretty bad quality, so swf seems wisest.

No doubt there's plenty of other ways it can be done...

How to use Flash scripts in my websites? Is it having separate coding?

You have to have a linux server. You have to install this
http://www.libming.org/
on it and then you can write scripts in either php or perl or the C-family which not only would enable you to manipulate fonts and graphics in the smoothest and most picture perfect way possible, but also can directly create "streaming video" - it actually creates SWF files, it's good for converting flv to swf, and you can even create animation directly, through programming code.

You need to be an advanced Linux administrator and an advanced perl or php programmer, and have experience in managing all sorts of file types, and you need to be in control of the settings of the whole server your site(s) are hosted on.

Basically, I am, rather typically, telling you to do highly complex and tricky stuff which you are not likely to be able to do for at least 36 different reasons... sorry. ;-)

Plus you're a different person to the first one, which makes it even more of a chances-are inappropriate piece of advice.