Update text in Flash with a form

I have a client that is uncomfortable with uploading .xml or .txt files, so I’d like to build a small little php script that will allow them to go to a “hidden” url (thiersite.com/secret/updatenews.php).

So, basically there will be a text field that will update the news on the flash site.

What is the best way to approach this? Any tutorials or existing modules to check out?

Thanks