Masking externally loaded dynamic text with external CSS applied.. (hlp)

Hello everyone, new poster here and l’ve got a question.
Now l’ve read the tutorials here and have been following along fairly well, but a problem has come up and l was wondering if anyone could help me out a bit here. or perhaps tell me some alternate methods used as ‘industry standards’.

l’m working on a full flash website and have come to a spot where l’d like to have the following things happening…

text loaded externally from a .txt file (no problem)
css loaded in for the text from a .css file (no problem)
then mask the textbox that contains this information (slight problem).

Here’s a zip with the source files of my example (4 total):
and here’s the resulting flash file:
(give it a moment to load angelfire is slow - you may need to cut and paste the URLs into your browser window as angelfire also won’t let you direct link :-p )
now everythings working ‘okay’… here’s what l’ve done.

Loaded in the external text…
loaded in the external css…

applied the css/text to the text area (which is inside of a movie clip).
Placed my “mask” layer over top of this movie clip and used actionscript:

to make a mask out of the “mask_mc”…
problem is that it is masking the entire bounding box of the mask_mc… is there a way around this, other than complicated mathimatical equations?

I have thought for certian l’ve seen dynamically loaded external content with CSS applied to it on other full flash sites (couple on l’m sure) that are masked with “unique” shapes… how is this done, if l’m not mistaken. any help would be greatly appriciated. Thanks for your efforts and your time.

Samantha Gram.