For java script: XML DOM
For PHP/MySQL: Database to hold post
For XML: to make RSS feeds
So I just came up with this last night on the top of my head. This will be the first time I'm writing it down so bare with me.
Basically what you have to do is to parse the RSS feed using XML DOM. To create a new item for the RSS feed, you would insert a new row to the database using PHP and SQL. After that section of the PHP program, declare a variable that would hold the source code for the "updated RSS feed"
$rss = "<? xml version="1.0" ?> \n"; $rss .= " <? rss version="2.0" ?> \n";
Basically that's what you would have to do. Please excuse the errors that might exist inside those values. I haven't written an XML in a while so I forgot what it was supposed to be like.
Now after the opening tags, you would insert the 6 most recent rows in the MySQL database. I prefer using 6 because isn't that the standard? I don't know maybe 15 but it can be any amount you want. Just don't make the file too big.
After you've done this, overwrite or create a new RSS file. And there you go.